S = input()
a = [v for v in S]
b = [(i,v) for i,v in enumerate(a) if v == 'c' or v == 'w']
r = len(b)
s = set()


for i,v in b:
    if v == 'c':
        j = 0
        k = b.index((i,v))
        while j < 2:
            k += 1
            if k == r:
                j = 2
            else:
                l = b[k]
                if l[1] == 'w':
                    j += 1

        if k < r:
            m = b[k]
            n = m[0] - i + 1
            s.add(n)

if len(s) == 0:
    print(-1)
else:
    o = min(s)
    print(o)