import sys


def input(): return sys.stdin.readline().rstrip('\n')


def main():
    def solve(x):
        r = g = 0
        for c in x:
            if c == 'R':
                r += 1
            elif c == 'G':
                if r == 0:
                    return False
                else:
                    r -= 1
                    g += 1
            elif c == 'W':
                g = max(0, g - 1)
            else:
                assert False
        return r == g == 0

    t = int(input())
    for _ in range(t):
        print('possible' if solve(input()[::-1]) else 'impossible')


if __name__ == '__main__':
    ret = main()
    if ret is not None:
        print(ret)