#!/usr/bin/env python
#coding:utf8


def read():
    return raw_input()


def work(s):
    chList = "WGR"

    val = [0, 0, 0]
    for ch in s:
        val[chList.find(ch)] += 1
        if not (val[0] >= val[1] >= val[2]):
            print "impossible"
            return

    wIdx = []
    gIdx = []
    for idx, ch in enumerate(s):
        if ch == 'W':
            wIdx.append(idx)
        elif ch == 'G':
            gIdx.append(idx)

    gIdxCursor = 0
    for idx in wIdx:
        while gIdxCursor < len(gIdx) and idx > gIdx[gIdxCursor]:
            gIdxCursor += 1
        if gIdxCursor == len(gIdx):
            print "impossible"
            return
    
    if val[0] >= val[1] and val[1] == val[2] and val[2] > 0 and s[-1] == 'R':
        print "possible" 
    else:
        print "impossible"


if __name__ == "__main__":
    for i in range(input()):
        work(read())