# 最小チワワ問題
str = input()
count = 0
wCount = 0
ans = 0
j = ''
for s in str:
  if(s=='c'):
    count=1
    j='w'
  elif(s=='w' and j=='w' and wCount!=2):
    count+=1
    wCount+=1
    if(wCount==2):
      ans=count
      count=0
      wCount=0
      j=0
  elif(j=='w'):
    count+=1
if(ans==0):
  print(-1)
else:
  print(ans)