Problem:
Score : 100 points

Problem Statement

Joisino wants to evaluate the formula "A op B".
Here, A and B are integers, and the binary operator op is either + or -.
Your task is to evaluate the formula instead of her.

Constraints

1≦A,B≦10^9

op is either + or -.

Input

The input is given from Standard Input in the following format:

A op B

Output

Evaluate the formula and print the result.

Sample Input 1

1 + 2

Sample Output 1

3

Since 1 + 2 = 3, the output should be 3.

Sample Input 2

5 - 7

Sample Output 2

-2

Solution in C (GCC 5.4.1) (judge verdict: Runtime Error)

#include <stdio.h>
#define mod 1000000007
 
int main(){
  int N;
  scanf("%d",&N);
  int a[(N+1)/2];
  int A;
  
  for(int i=0;i<(N+1)/2;i++) a[i]=0;
  for(int i=0;i<N;i++){
    scanf("%d",&A);
    a[A/2]++;
  }
 
  int flag=1;
  int cnt=0;
  for(int i=0;i<(N+1)/2;i++){
    if(i==0&&N%2!=0){
      if(a[i]!=1)
        flag=0;
    }
    else{
      if(a[i]!=2) flag = 0;
      else cnt++;
    }
  }
  long long ans=1;
  while(cnt>0){
    ans*=2;
    ans%=mod;
    cnt--;
  }
  if(flag){
    printf("%lld\n",ans);
  }
  else{
    printf("0\n");
  }
  return 0;
}