AC

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