import sys, os

I = list(map(int, sys.stdin.read().strip()))

def sum_n(a, b):
    return (b-a+1)*(a+b)//2

idxs = []
b = 0
for i in I:
    idxs.append(b)
    b += i

res = 0
id = len(I)//2  # last id
for j in range(len(I)-1,-1,-2):  # backward
    fsize = I[j]
    for i in range(1, j, 2):  # find free space forward
        if I[i] >= fsize: # enough free space
            b = idxs[i]
            res += sum_n(b, b+fsize-1)*id
            idxs[i] += fsize
            I[i] -= fsize
            break
    else:  # block too big stays where it is
        b = idxs[j]
        res += sum_n(b, b+fsize-1)*id
    id -= 1

print(res)