from atcoder.fenwicktree import FenwickTree
s=list(input())
n=len(s)
ft=FenwickTree(n)
for i in range(n):
    if s[i]=="0":
        ft.add(i,1)
rle=[]
rle.append([s[0],0])
for i in range(n):
    if rle[-1][0]==s[i]:
        rle[-1][-1]+=1
    else:
        rle.append([s[i],1])
ans=0
cnt=0
for i,j in rle:
    cnt+=j
    if i=="1":
        j//=2
        ans+=ft.sum(cnt,n)*j
print(ans)