for _ in range(int(input())):
    
    S = input()
    
    x = False
    y = False
    for s in reversed(S):
        
        if s == 'R':
            if x == False:
                x = 0
            x += 1
        elif s == 'G':
            if x:
                x -= 1
                if y == False:
                    y = 0
                y += 1
            else:
                x = -1
                break
            
        else:
            if y is False:
                x = -1
                
                break
            if y > 0:
                y -= 1
    if x == 0 and y <= 0:
        print('possible')
    else:
        print('impossible')