for _ in range(int(input())):
    x = list(input())
    y = list(input())
    xx = x + x
    yy = y + y
    n = min(len(x),len(y))*2
    cnt = 0
    for i in range(n):
        cnt += xx[i] == yy[i]
    if cnt != n:
        if xx > yy:
            print("X")
        elif xx < yy:
            print("Y")
    else:
        if len(x) > len(y):
            print("X")
        else:
            print("Y")