s=input()
w='cww'
l=[]
p=[]
v=-1
for i,j in enumerate(s):
  if j in w:
    l+=[j]
    l=l[-3:]
    p+=[i]
    p=p[-3:]
    if ''.join(l)==w:
      v=max(p)-min(p)+1
      break
print(v)