题解

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