S = input()
WCNT = 0
ANS = 100
for N, SC in enumerate(S):
  WCNT = 0
  LENGTH = 1
  if(SC == 'c'):
    for SW in S[N + 1:]:
      LENGTH += 1
      if(SW == 'w'):
        WCNT += 1
      if(WCNT == 2):
        if(ANS > LENGTH):
          ANS = LENGTH
if(ANS == 100):
  print(-1)
else:
  print(ANS)