T = int(input())
for _ in range(T):
    S = list(input())
    cntR = S.count("R")
    cntG = S.count("G")
    cntW = S.count("W")
    if cntR != cntG or cntR == 0 or cntW < cntG:
        print("impossible")
        continue
                
    flag = 1
    nR, nW, nG = 0, 0, 0
    for s in S:
        if s == "G":
            nG += 1
        elif s == "R":
            nR += 1
        else:
            nW += 1
        
        if nW < nG or nG < nR or (cntG == nG and cntW != nW) or (cntR == nR and cntW != nW):
            print("impossible")
            flag = 0
            break
    if flag == 0:
        continue
    print("possible")