include <stdio.h>
int main() {
int a, b, c, d, e, f, g, h, i, j, k, n;
scanf("%d", &a);
b = a % 10;
c = a / 10;
d = c % 10;
e = c / 10;
f = e % 10;
g = e / 10;
h = g % 10;
i = g / 10;
j = i % 10;
k = i / 10;
n = b + d + f + h + j;
printf("%d", n);
return 0;
}