jijibo

#include <iostream>
#include <string>
using namespace std;
int main(){
    string s;
    cin >> s;
    int len = s.length();
    for(int i = 0; i < len; i++){
        if(s[i] == 'A'){
            cout << 'T';
        }else if(s[i] == 'T'){
            cout << 'A';
        }else if(s[i] == 'G'){
            cout << 'C';
        }else if(s[i] == 'C'){
            cout << 'G';
        }
    }
    return 0;
}