s=input()
n=len(s)
cnt=0
ans=10000 
for i in range(0,n-2): 
    if s[i]=="c": 
        cnt-=i
        for j in range(i+1,n-1):
            if s[j]=="w":
                for k in range(j+1,n):
                    if s[k]=="w":
                        cnt+=k+1
                        ans=min(ans,cnt)
if ans==10000:print(-1)
else:print(ans)