w = list(input())

c_idx = [n for n, i in enumerate(w) if i == 'c']
w_idx = [n for n, i in enumerate(w) if i == 'w']

if w[c_idx[0]:].count('w') < 2:
    print(-1)

else:
    ls = []
    for i in c_idx:
        if len([j for j in w_idx if j > i]) < 2:
            break
        else:
            wls = [j for j in w_idx if j > i]
            ls.append(wls[1] - i + 1)
                  
    print(min(ls))