S = input()

ans = []
c = 0

for i in range(len(S)):
    if S[i] == 'c':
        tmp = i
        c = 0
        for j in range(i + 1, len(S)):
            if S[j] == 'w':
                c += 1
            if c == 2:
                ans.append(j - i + 1)
                break
        

print(min(ans) if len(ans) > 0 else -1)