#include<bits/stdc++.h>
using namespace std;
int l,i,b; char a[265];
int main() {
cin>>a;
l=strlen(a);
for(i=0;i<=l-1;i++)
{
if(a[i]=='A')
a[i]='T';
else if(a[i]=='T')
a[i]='A';
else if(a[i]=='G')
a[i]='C';
else if(a[i]=='C')
a[i]='G';
}
cout<<a;
return 0;
}