///afin
#include <fstream>
#include <cstring>
using namespace std;
ifstream in("afin.in");
ofstream out("afin.out");
int a,b;
char s[10001];
int main()
{
    int i,l;
    in>>a>>b;
    in>>s;
    l=strlen(s);
    for(i=0; i<l; i++)
        s[i]='a'+((a*(s[i]-'a')+b)%26);
    out<<s;
    in.close();
    out.close();
    return 0;
}