include <stdio.h>

int main() {

int  a, b, c, d, e, f;
scanf("%d", &a);
b = a % 10;
a = a / 10;
c = a % 10;
a = a / 10;
d = a % 10;
a = a / 10;
e = a % 10;
f = b + c + d + e;
printf("%d", f );

return 0;

}