#!/usr/bin/env python3
def is_possible(s):
    w0 = 0
    w1 = False
    g = 0
    r = 0
    for c in s:
        if c == 'W':
            w0 += 1
            w1 = True
        elif c == 'G':
            if not w0:
                return False
            w1 = False
            w0 -= 1
            g  += 1
        elif c == 'R':
            if not g:
                return False
            g -= 1
            r += 1
    if w1 or g:
        return False
    return True


t = int(input())
for _ in range(t):
    s = input()
    print('possible' if is_possible(s) else 'impossible')