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

int main(){
	int t;
	cin >> t;
	while (t--){
		int r;
		int ans = 0;
		cin >> r;
		string s;
		cin >> s;
		int len = s.size();
		for (int i = 0; i < len; i++){
			if (s[i] >= '0' && s[i] <= '9'){
				ans += pow(r,len-i-1)*int(s[i]-'0');
			}else{
				ans += (s[i]-'A'+10)*pow(r,len-i-1);
			}
		}
		cout << ans << endl;
	}
	return 0;
}