def solve(S):
    w,g,r=0,0,0
    for s in S[::-1]:
        if s=='R':
            r+=1
        elif s=='G':
            g+=1
            if g>r:
                return False
        elif g==0:
            return False
        elif w<g:
            w+=1
    return w==g==r

n = int(input())
for i in range(n):
    if solve(input().strip()):
        print("possible")
    else:
        print("impossible")