### A. Currency System in Geraldion

A magic island Geraldion, where Gerald lives, has its own currency system. It uses banknotes of several values. But the problem is, the system is not perfect and sometimes it happens that Geraldionians cannot express a certain sum of money with any set of banknotes. Of course, they can use any number of banknotes of each value. Such sum is called unfortunate. Gerald wondered: what is the minimumunfortunate sum?

#### Input

The first line contains number n (1 ≤ n ≤ 1000) — the number of values of the banknotes that used in Geraldion.

The second line contains n distinct space-separated numbers a1, a2, …, an (1 ≤ ai ≤ 106) — the values of the banknotes.

#### Output

Print a single line — the minimum unfortunate sum. If there are no unfortunate sums, print  - 1.

Java代码：

```import java.util.Scanner;

public class Main {
public static void main(String[] args) {
Scanner cin = new Scanner(System.in);
int n = cin.nextInt();
boolean ok = false;
for (int i = 0; i &lt; n; i++) {
int x = cin.nextInt();
if(x == 1) ok = true;
}
if(ok) System.out.println("-1");
else System.out.println("1");
}
}
```

### B. Gerald is into Art

Gerald bought two very rare paintings at the Sotheby’s auction and he now wants to hang them on the wall. For that he bought a special board to attach it to the wall and place the paintings on the board. The board has shape of an a1 × b1 rectangle, the paintings have shape of a a2 × b2 and a3 × b3 rectangles.

Since the paintings are painted in the style of abstract art, it does not matter exactly how they will be rotated, but still, one side of both the board, and each of the paintings must be parallel to the floor. The paintings can touch each other and the edges of the board, but can not overlap or go beyond the edge of the board. Gerald asks whether it is possible to place the paintings on the board, or is the board he bought not large enough?

#### Input

The first line contains two space-separated numbers a1 and b1 — the sides of the board. Next two lines contain numbers a2, b2, a3 and b3— the sides of the paintings. All numbers ai, bi in the input are integers and fit into the range from 1 to 1000.

#### Output

If the paintings can be placed on the wall, print “YES” (without the quotes), and if they cannot, print “NO” (without the quotes).

CPP代码：

``` #include <bits/stdc++.h>
using namespace std;

int x, y, x1, y1, x2, y2;

bool in(int a, int b) {
return (a <= x && b <= y) || (a <= y && b <= x);
}

bool judge() {
int a, b;
a = x1 + x2, b = max(y1, y2);
if(in(a, b)) return true;

swap(x1, y1);
a = x1 + x2, b = max(y1, y2);
if(in(a, b)) return true;

swap(x2, y2);
a = x1 + x2, b = max(y1, y2);
if(in(a, b)) return true;

swap(x1, y1);
a = x1 + x2, b = max(y1, y2);
if(in(a, b)) return true;

return false;
}

int main() {
cin >> x >> y >> x1 >> y1 >> x2 >> y2;
if(judge()) puts("YES");
else puts("NO");
return 0;
}
```

### C. Gerald’s Hexagon

Gerald got a very curious hexagon for his birthday. The boy found out that all the angles of the hexagon are equal to 120*. Then he measured the length of its sides, and found that each of them is equal to an integer number of centimeters. There the properties of the hexagon ended and Gerald decided to draw on it.

He painted a few lines, parallel to the sides of the hexagon. The lines split the hexagon into regular triangles with sides of 1 centimeter. Now Gerald wonders how many triangles he has got. But there were so many of them that Gerald lost the track of his counting. Help the boy count the triangles.

#### Input

The first and the single line of the input contains 6 space-separated integers a1, a2, a3, a4, a5 and a6 (1 ≤ ai ≤ 1000) — the lengths of the sides of the hexagons in centimeters in the clockwise order. It is guaranteed that the hexagon with the indicated properties and the exactly such sides exists.

#### Output

Print a single integer — the number of triangles with the sides of one 1 centimeter, into which the hexagon is split.

CPP代码：

```#include &lt;bits/stdc++.h&gt;
using namespace std;

int a, b, c, d, e, f;

int main() {
cin &gt;&gt; a &gt;&gt; b &gt;&gt; c &gt;&gt; d &gt;&gt; e &gt;&gt; f;
int res = 0;
int x1 = min(b, f), y1 = a;
res += x1*x1 + 2*x1*y1;
// cout &lt;&lt; res &lt;&lt; endl;
int x2 = min(e, c), y2 = d;
res += x2*x2 + 2*x2*y2;
// cout &lt;&lt; res &lt;&lt; endl;
int x3 = max(b, f)-x1, y3 = y1+x1;
res += 2 * x3 * y3;
cout &lt;&lt; res &lt;&lt; endl;
return 0;
}
```

### D. Equivalent Strings

Today on a lecture about strings Gerald learned a new definition of string equivalency. Two strings a and b of equal length are calledequivalent in one of the two cases:

1. They are equal.
2. If we split string a into two halves of the same size a1 and a2, and string b into two halves of the same size b1 and b2, then one of the following is correct:
1. a1 is equivalent to b1, and a2 is equivalent to b2
2. a1 is equivalent to b2, and a2 is equivalent to b1

As a home task, the teacher gave two strings to his students and asked to determine if they are equivalent.

#### Input

The first two lines of the input contain two strings given by the teacher. Each of them has the length from 1 to 200 000 and consists of lowercase English letters. The strings have the same length.

#### Output

Print “YES” (without the quotes), if these two strings are equivalent, and “NO” (without the quotes) otherwise.

CPP代码：

```#include &lt;bits/stdc++.h&gt;
using namespace std;

char s;
char t;

bool isEuqal(int a, int b, int len) {
if(strncmp(s+a, t+b, len) == 0) return true;
if(len % 2 == 1) return false;
int l = len &gt;&gt; 1;
if(isEuqal(a, b, l) &amp;&amp; isEuqal(a+l, b+l, l)) return true;
if(isEuqal(a+l, b, l) &amp;&amp; isEuqal(a, b+l, l)) return true;
return false;
}

int main() {
scanf("%s %s", s, t);
int len1 = strlen(s), len2 = strlen(t);
if(len1 == len2 &amp;&amp; isEuqal(0, 0, len1)) puts("YES");
else puts("NO");
return 0;
}
```