#include<bits/stdc++.h>
using namespace std;
char a[10010];
int main()
{ 
     int ans=0;
    cin>>a;
    int len=strlen(a);
	for(int i=0;i<len;i++)
	{
		if(a[i]=='T') cout<<"A";
		if(a[i]=='A') cout<<"T";
		if(a[i]=='G') cout<<"C";
		if(a[i]=='C') cout<<"G";
	}
	return 0;
}