count = int(input())
result = []

for i in range(count):
    memo = input()
    judge = 0
    for char in reversed(memo):
        if char == 'R':
            judge += 1
        elif char == 'G':
            judge -= 1
        
        if judge < 0:
            break
    if judge < 0:
        result.append("impossible")
    else:
        result.append("possible")
for r in result:
    print(r)