#include<bits/stdc++.h> using namespace std; int main() { int x; string s; cin>>x>>s; int ans=0; for(int i = 0;i < s.size();++i){ if(s[i] >='0' && s[i] <='9')ans = ans *x+s[i]-'0'; else ans =ans*x+s[i]-'A'+10; } cout<<ans; return 0; }