#include<bits/stdc++.h> using namespace std; int main(){ string s; int x; int ans=0; cin>>x>>s; 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; }