for i in range(int(input())):
    s = input()
    w, g, r, l = 0, 0, 0, s.count("G")
    f = 1 if s.count("G") != s.count("R") or s[0] != "W" else 0
    for j in s:
        if f > 0 : break 
        if j == "W":
            w += 1
            if l == 0:
                f = 1
        if j == "G":
            if l > 0 and w > 0:
                w -= 1; l -= 1; g += 1
            else:
                f = 1
        if j == "R":
            if g > 0:
                g -= 1; r += 1
            else:
                f = 1
    print("possible" if f == 0 and r == s.count("G") else "impossible")