def determine_winner(test_cases): results = [] for case in test_cases: n, s = case if n < 3: results.append("X") continue found = False for i in range(n - 2): triplet = s[i:i+3] c_o = triplet.count('o') e = triplet.count('-') added_o = (e + 1) // 2 if c_o + added_o >= 3: results.append("O") found = True break if not found: results.append("X") return results def main(): import sys input = sys.stdin.read().split() ptr = 0 T = int(input[ptr]) ptr +=1 test_cases = [] for _ in range(T): N = int(input[ptr]) ptr +=1 S = input[ptr] ptr +=1 test_cases.append( (N, S) ) results = determine_winner(test_cases) print('\n'.join(results)) if __name__ == "__main__": main()