#include<bits/stdc++.h> using namespace std; int main(){ int r,k=0,sum=0; string s; cin>>r>>s; int lens = s.size(); for(int i=lens-1;i>=0;i--){ if('0'<=s[i]&&s[i]<='9'){ sum += (s[i]-'0')*pow(r,k); } else if(s[i]>='A'){ sum += (s[i]-55)*pow(r,k); } k++; } cout<<sum; return 0; }