#include <stdio.h>
int main()
{
int n = 0;
scanf("%d",&n);
int i =0;
int j = 0;
for(i=4;i>0;i--)
{
j = j +n%10;
n /= 10;
}
printf("%d",j);
return 0;
}

#include <stdio.h>
int main()
{
int n = 0;
scanf("%d",&n);
int i =0;
int j = 0;
for(i=4;i>0;i--)
{
j = j +n%10;
n /= 10;
}
printf("%d",j);
return 0;
}