import sys
input=lambda: sys.stdin.readline().rstrip()
S=input()
n=len(S)
C=[]
W=[]
import bisect
for i in range(n):
  if S[i]=="c":
    C.append(i)
  if S[i]=="w":
    W.append(i)
ans=float("inf")
for i in range(len(W)-1):
  w1,w2=W[i],W[i+1]
  if w1<C[0]:
    continue
  else:
    c=C[bisect.bisect_left(C,w1)-1]
    ans=min(ans,w2-c+1)
print(-1 if ans==float("inf") else ans)