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