st=input()
cnt=0
flg=0
ans=[]
try:
    for i in range(len(st)):
        if st[i]=="c":
            cix=i
            flg=1
        elif st[i]=="w" and flg==1:
            cnt+=1

        if cnt==2:
            ans.append(i-cix+1)
            cnt=0
            flg=0
    print(min(ans))
except:
    print(-1)