#include<bits/stdc++.h>
using namespace std;
typedef long long LL;
LL trans(string s,int x)
{
	//reverse(s.begin(),s.end());
	LL res=0;
	//cout<<s<<endl;
	for(int i=0;i<s.size();i++)
	{
		int t=0;
		if(s[i]>='0'&&s[i]<='9')
		{
			t=s[i]-'0';	
		}	
		else
		{
			t=s[i]-'A'+10;
		}
		res=res*x+t;
	//	cout<<t<<endl;
	//	cout<<res<<endl; 
	}	
	return res;
} 
int main()
{
	int T;
	cin>>T;
	while(T--)
	{
		int x;
		string s;
		cin>>x>>s;
		cout<<trans(s,x)<<endl; 
	}
	return 0;
}