242

#include<bits/stdc++.h>
using namespace std;
int main(){
    string data;
    unsigned long long result = 0;
    int from , to ;
    cin >> from >> to >> data;

    if(from != 10){
        for(int i=data.length()-1; i>=0;i--){
            string temp="";temp+=data[i];
            result += stoi(temp) * pow(from ,data.length()-1-i );
        }
        cout << result << endl;
    }
    return 0;
}