#include<iomanip> 
#include<cmath> 
#include<cstdio> 
#include<cstring> 
#include<algorithm> 
const int N=1e7+8;
const int INF=0x3f3f3f3f;
using namespace std;
int n,m;
char a[N],b[N];
int main()
{
	cin>>a;
	int len=strlen(a);
	for(int i=0;i<len;i++)
	{
		if(a[i]=='A')
		{
			b[i]='T';
		}
		else if(a[i]=='T')
		{
			b[i]='A';
		}
		else if(a[i]=='G')
		{
			b[i]='C';
		}
		else if(a[i]=='C')
		{
			b[i]='G';
		}
	}
	cout<<b;
	return 0;
}