#coding: utf-8
##yuki_345

s=list(raw_input())
sc=[]
sw=[]
r=[]

for i in xrange(len(s)):
 if s[i]=='c':
  sc.append(i)
 elif s[i]=='w':
  sw.append(i)

res=100
res_t=100
for i in xrange(len(sc)):
 rt=[]
 for j in xrange(len(sw)):
  if sc[i]<sw[j]:
   rt.append(sw[j])
 if len(rt)>1:
  res_t=rt[1]-sc[i]
 if res_t<res:
  res=res_t

if res==100:
 print -1
else:
 print res+1