[BOJ/백준] 12933 오리

string = input()
duck = 'quack'
cnt = 0
result = []
answer = 0
for st in string:
    flag = True
    for ind in range(len(result)):
        if duck[(duck.index(result[ind][-1])+1)%5] == st:
            result[ind].append(st)
            flag = False
            break
 
    if flag:
        if st != 'q':
            answer = -1
            break
        result.append([st])
 
if answer == -1:
    print(answer)
else:
    for i in result:
        if len(i)%5 != 0:
            print(-1)
            break
    else:
        print(len(result))
 
    
 

S = input()
 
duck = {'q':0,'u':1,'a':2,'c':3,'k':4}
 
queue = []
answer = 0
for sound in S:
    flag = True
    for ind in range(len(queue)):
        if (queue[ind] + 1)%5 == duck[sound]:
            queue[ind] = (queue[ind] + 1)%5
            flag = False
            break
    if flag:
        if duck[sound] != 0:
            answer = -1
            break
        queue.append(0)
 
 
if answer == -1:
    print(-1)
else:
    for num in queue:
        if num != 4:
            print(-1)
            break
    else:
        print(len(queue))