t = int(input())
tr = ["o" + "-" * (2 ** i - 1) + "o" for i in range(2, 11)]
for _ in range(t):
  _, S = input().split()
  if any(i in S for i in ["oo-","-oo","ooo","o-o","--o-","-o--"] + tr):
    print("O")
  else:
    print("X")