import math
N=list(input())
running=True
ans=0
while running:
  try:
    c1=N.index('c')
    running=True
    del N[0:c1+1]
  except:
    running=False
  if running:
    try:
      ww=N.count("w")
      if ww<=1:
        running=False
      else:
        w_comb=math.comb(ww,2)
        ans+=w_comb
    except:
      running=False
if ans==0:
  ans=-1
print(ans)