s = input()

c = []
w = []
for i in range(len(s)):
    if s[i] == 'c':
        c.append(i)

for i in range(len(s)):
    if s[i] == 'w':
        w.append(i)

if len(c) != 1 or len(w) < 2 or c[0] > w[0]:
    print(-1)
else:
    print(w[1] - c[0] + 1)