t=int(input())
for _ in range(t):
    flg=True
    s=list(input())
    n=len(s)
    w=0
    g=0
    r=0
    for i in range(n):
        if s[i]=='W': w+=1
        elif s[i]=='G': 
            g+=1
            w-=1
        elif s[i]=='R': 
            r+=1
            g-=1
        if w<0 or g<0:
            flg=False
            break
    if flg==False or r==0 or g>0 or s[-1]=='W':
        print('impossible')
    else:
        print('possible')