#include<bits/stdc++.h>
using namespace std;

int main()
{
	int n;
	cin>>n;
	while(n--){
		int x;
		cin>>x;
		string a;
		cin>>a;
		int sum = 0;
		int ans = a.size() - 1;
		for(int i = 0;i < a.size();i++){
			if(a[i] >= 'A' && a[i] <= 'F'){
				sum += (a[i] - 55) * pow(x, ans);
			}else{
				sum += (a[i] - 48) * pow(x, ans);
			}
			ans--;
		}
		cout<<sum<<endl;
	}
	return 0;
}