#include <iostream>
#include <string>
using namespace std;

int mtoD(string s, int m){
	int ans = 0;
	for(int i = 0; i <= s.size() - 1; i++){
		if('0' <= s[i] && s[i] <= '9') ans = ans * m + s[i] - '0';
		else ans = ans * m + s[i] - 'A' + 10;
	}
	return ans;
}

int main(){
    int N;
    cin >> N;
    while(N--){
        int K;
        string s;
        cin >> K >> s;
        cout << mtoD(s, K) << endl;
    }
    return 0;
}