s = input()
c = False
cpos = 0
w = False
li = []
for i, v in enumerate(s):
    if c and w:
        if v == "w":
            li.append(i - cpos + 1)
    elif c:
        if v == "w":
            w = True
        elif v == "c":
            cpos = i
    else:
        if v == "c":
            cpos = i
            c = True

if len(li) >= 1:
    print(min(li))
else:
    print('-1')