def check(str):
    if str.count('R') != str.count('G'): return 'impossible'
    elif str.count('W') < str.count('R'): return 'impossible'
    elif str.count('W') * str.count('R') * str.count('G') == 0: return 'impossible'
    else:
        coming_green = False
        coming_red = 0
        for s in str:
            if s == 'W':
                coming_green = True
            elif s == 'G':
                if coming_green == False:
                    return 'impossible'
                else:
                    coming_green = False
                    coming_red += 1
            elif s == 'R':
                if coming_red < 1:
                    return 'impossible'
                else:
                    coming_red -= -1
    
    return 'possible' 
                
T = input()
for t in range(T):
    print check(raw_input())