#include <iostream>
#include <vector>

using namespace std;

char char_pos(string &word, int word_s, vector<char> &naredbe, int trazena) {
    if(trazena < word_s) return word[trazena];

    // word_s * 2^pow
    int inf = word_s;
    int pow = 0;
    if(trazena != inf) {
        while(trazena > inf) {
            inf*=2;
            pow++;
        }
        inf/=2;
        pow--;
    }

    char c = char_pos(word, word_s, naredbe, trazena - inf);
    if(naredbe[pow]=='C') {
        if(c == 'A') c = 'T';
        else if(c == 'T') c = 'A';
        else if(c == 'C') c = 'G';
        else if(c == 'G') c = 'C';
    }
    return c;
}

int main() {
    int n;
    int k;
    string s;
    cin >> n >> k >> s;

    vector<char> a(n);
    for(char &c : a) cin >> c;

    cout << char_pos(s,s.size(), a, k) << endl;
    return 0;
}