n=int(input())
#n=1

for i in range(n):
    s=input()
    g=0
    r=0
    w=0
    w2=0
    f=1
    se=set()
    for i in s:
        se.add(i)
        if i == 'W':
            w+=1
            w2+=1
        elif i == 'G':
            g+=1
            w2 = 2
        elif i == 'R':
            r+=1
            w2%=2
        if (g - r) < 0:
            f = 0
        if (w-g) < 0:
            f = 0
                
    if ((g-r) != 0) or (f == 0) or (len(se) == 1) or (len(s) < 3) or (w<g) or (w2!=0):
        #print(((g-r) != 0) , (f == 0) , (len(se) == 1) , (len(s) < 3) , (w<g) , (w2!=0),w2,g,r)
        print('impossible')
    else:
        print('possible')