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

using ll = long long;
using ull = unsigned long long;
using ld = long double;
template<class t> using vc = vector<t>;
template<class t> using vvc = vc<vc<t>>;
using pi = pair<int,int>;
using vi = vc<int>;
using vvi = vvc<int>;

#define rep(i,a,b) for (int i = a; i < b; i++)
#define irep(i,a,b) for (int i = a; i > b; i--)
#define print(n) cout << n << endl
#define rup(a,b) (a+b-1)/b

void solve(){
    string x,y;cin>>x>>y;
    string p = "X";
    string q = "Y";
    if (x.size()<y.size()) {swap(x,y);swap(p,q);}
    int a,b;
    int now = 0;
    while (true){
        a = int(x[now%x.size()]-'a');
        b = int(y[now%y.size()] - 'a');
        if (a<b) print(q);
        else if(a>b) print(p);
        else {
            now ++;
            if (now%x.size()==x.size()-1 && now%y.size()==y.size()-1) break;
            continue;
        }
        return;
    }

    print(p);
    return;
}

int main(){
    cout << fixed << setprecision(15);
    
    int T;
    cin >> T;
    rep(i,0,T) solve();
    
    //system("pause");
    return 0;
}