Problem:
Score : 100 points

Problem Statement

On the Planet AtCoder, there are four types of bases: A, C, G and T. A bonds with T, and C bonds with G.

You are given a letter b as input, which is A, C, G or T. Write a program that prints the letter representing the base that bonds with the base b.

Constraints

b is one of the letters A, C, G and T.

Input

Input is given from Standard Input in the following format:

b

Output

Print the letter representing the base that bonds with the base b.

Sample Input 1

A

Sample Output 1

T

Sample Input 2

G

Sample Output 2

C

Solution in C (GCC 5.4.1) (judge verdict: Wrong Answer)

#include <stdio.h>
int main(void){
  char S[10];
  int len,out;
  out=0;
  scanf("%s",S);
  for(int i=0;i<=9;++i){
    len=0;
    for(int j=i;j<=9;++j){
      if(S[j]=='A' || S[j]=='C' || S[j]=='G' || S[j]=='T'){
        ++len;
      }else{
        if(len>out){
          out=len;
        }
        if(S[j]=='\0'){
          printf("%d",out);
          return 0;
        }
        len=0;
      }
    }
  }
  printf("%d",out);
  return 0;
}