n=int(input())

for i in range(n):
    s=input()
    g=0
    f=1
    for i in s:
        if i == 'G':
            g+=1
        elif i == 'R':
            g-=1
        if g < 0:
            f = 0
                
    if g != 0 or f == 0:
        print('impossible')
    else:
        print('possible')