s = input()
l = list(s)
del l[:l.index('c')]

if l.count('c') >= 1 and l.count('w') >= 2 and l.index('c') < l.index('w'):
    l.remove('w')
    print(len(l[l.index('c'):l.index('w')]) + 2)
else:
    print(-1)