#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_t=100
res=100
for i in xrange(len(sc)):
 rt=[]
 for j in xrange(len(sw)):
  if sw[j]>sc[i]:
   x=sw[j]-sc[i]
   rt.append(x)
 if len(rt)>1:
  if res_t>rt[1]:
   res=rt[1]
  
if res==100:
 print -1
else:
 print res+1