s = []
N = list(input())[::-1]
if N.count("wcwc") > 0:
    s += 4
if N.count("wwc") > 0:
    s += 3
M1_flg = 1
m1 = m2 = 0
for i, n in enumerate(N):
    if n == "w" and M1_flg == 1:
        m1 = i
        M1_flg = 2
    elif n == "w" and M1_flg == 2:
        m2 = i
        M1_flg = 3
    elif n == "w" and M1_flg == 3:
        m1 = m2
        m2 = i
    elif n == "c" and M1_flg == 3:
        s += [i - m1 + 1]
        m1 = i
        M1_flg = 1
print(min(s) if len(s) != 0 else -1)