#define LL long long
using namespace std;
const int N = 1010;
int n;
LL solve(int k, string s){
    LL res = 0;
    for(int i=0;i<s.size();i++){
        char c = s[i];
        int num;
        if(c >= '0' && c <= '9') num = c - '0';
        else num = c - 'A' + 10;
        res = res * k + num;
    }
    return res;
}
int main(){
    cin>>n;
    while(n--){
        int k;
        string s;
        cin>>k>>s;
        cout<<solve(k,s)<<endl;
    }
    return 0;
}
//:)
//114514
`

包AC