s=input()
l=len(s)
m=1000
while 1:
 c=s.find('c')
 w=s.find('w')
 v=s.find('w',w+1)
 if c<w<v and c!=-1 and v!=-1:m=min(m,v-c+1)
 else:break
 s=s[c+1:]
print(m if m!=1000 else -1)