s=input()
ch_c=None
ch_w=None
ch_w2=None
ans=float("INF")
for i in range(len(s)):
    if s[i]=="c":
        ch_c=i
    elif s[i]=="w":
        if ch_w != None:
            ans=min(ans,i-ch_w+1)
        elif ch_c != None:
            ch_w=ch_c
print([ans,-1][ans==float("INF")])