#include<bits/stdc++.h>
using namespace std;
long long l,s,q=1,y;
string x;
int main()
{
	cin>>y;
	cin>>x;
	l=x.size();
	for(int i=l-1;i>=0;i--)
	{
		if(x[i]>='0'&&x[i]<='9')
		{
			s+=(x[i]-48)*q;
		}
		else s=s+(x[i]-55)*q;
		{
			q*=y;
		}
	}
	cout<<s;
}

你是GAY