S = input()
ans = 200
i1 = i0 = -10000
for i in range(len(S)):
    if S[i] == 'c':
        i0 = i
    elif S[i] == 'w':
        ans = min(ans, i-i1+1)
        i1 = i0
if ans == 200:
    print(-1)
else:
    print(ans)