s=list(input())
ans=[]
for i in range(len(s)):
  if s[i]=='c':
    ct=0
    for j in range(i+1,len(s)):
      if s[j]=='w':
        ct+=1
      if ct==2:
        ans.append(j-i+1)
        break
if ans:
  print(min(ans))
else:
  print(-1)