s = raw_input()
l = []
for i in range(len(s)):
    if s[i] == 'c':
        w = 0
        for j in range(i+1,len(s)):
            if s[j] == 'w':
                w += 1
            if w == 2:
                l.append(j-i+1)
                break
if l == []:
    print -1
else:
    print min(l)