import sequtils,strutils
var
    N = stdin.readline.parseInt
    s : string
for n in 0..<N:
    s = stdin.readline
    var
        w,g,r,w2 : int
    for c in s:
        if c == 'W':
            w += 1
            w2 += 1
        if c == 'G':
            w = 0
            if w2 > 0:
                w2 -= 1
            else:
                w = 1
                break
            g += 1
        if c == 'R':
            g -= 1
        if g < 0:
            break
    if w == 0 and g == 0:
        echo "possible"
    else:
        echo "impossible"