#include<bits/stdc++.h> using namespace std; int main(){ string s1,s2; cin>>s1; for(int i=0;i<s1.length();i++){ if(s1[i]=='T') s2[i]='A'; else if(s1[i]=='A') s2[i]='T'; else if(s1[i]=='G') s2[i]='C'; else s2[i]='G'; cout<<s2[i]; } return 0; }