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