#include<bits/stdc++.h> using namespace std; char a[260]; int main() { cin>>a; for(int i=0;i<strlen(a);i++){ if(a[i]=='A'){ cout<<"T"; }else if(a[i]=='T'){ cout<<"A"; }else if(a[i]=='G'){ cout<<"C"; }else{ cout<<"G"; } } return 0; }