#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]>='0'&&s[i]<='9')ans = ans * R+s[i]-'0'; else ans = ans * R+s[i] -'A'+10; } cout<<ans; return 0; }