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