INF = float("inf")
def solve():
    s = input()
    ans = INF
    li = [-1] * 4
    while True:
        for i, a in enumerate("cww", start=1):
            li[i] = s.find(a, li[i - 1] + 1)
            if li[i] == -1:
                return ans
        ans = min(ans, li[3] - li[1] + 1)
        li[0] = li[1]
    return ans
ans = solve()
print(ans if ans != INF else -1)