s=input()
n=len(s)
cnt=0
ans=10000
for i in range(n):
    if s[i]=="c":
        cnt-=i
        for j in range(i+1,):
            if s[j]=="w":
                if s[j]=="w":
                    cnt+=j
                    ans=min(ans,cnt)
if ans==0:print(-1)
else:print(ans)