T = int(input())

for i in range(T):
    s = input()    
    L = len(s)
    cnt = 0
    g = 0
    w = 0
    if s[0] != 'W':
        print('impossible')
        continue
    for i in range(L-1, -1, -1):
        if s[i] == 'R':
            cnt += 1
        elif s[i] == 'G':
            cnt -= 1
            g += 1        
        elif s[i] == 'W' :
            w += 1
            if g == 0:
                print('impossible')
                break
        if cnt < 0:
            print('impossible')      
            break      
            
    else:
        if cnt == 0 and g <= w:
            print('possible')
        else:
            print('impossible')