s = []
N_flg = 1
m = 0
for i, n in enumerate(input()):
    if n == "c":
        m = i
        N_flg = 2
    elif n == "w" and N_flg == 2:
        N_flg = 3
    elif n == "w" and N_flg == 3:
        s += [i - m + 1]
        N_flg = 1
print(min(s) if len(s) != 0 else -1)