# coding: utf-8


def main():
    N = list(input())
    n = []
    ans = 101
    for s in range(len(N)):
        if N[s] == 'c':
            for t in range(s+1,len(N)):
                if N[t] == 'w':
                    for u in range(t+1,len(N)):
                        if N[u] == 'w':
                            n.append(u - s + 1)
    print(-1) if ans - len(n) == 101 else print(min(n))

if __name__ == '__main__':
    main()