from collections import Counter


def solve(s: str) -> bool:
    t = Counter()
    used_g = False
    for c in reversed(s):
        match c:
            case 'W':
                if not used_g: return False
                if t['G'] > 0:
                    t['G'] -= 1
            case 'G':
                if t['R'] == 0: return False
                used_g = True
                t['R'] -= 1
                t['G'] += 1
            case 'R':
                t['R'] += 1

    if t['R'] or t['G']: return False
    return True


T = int(input())
for _ in range(T):
    S = input()
    if solve(S):
        print('possible')
    else:
        print('impossible')