C++ :

#include <iostream> 
#include <cstdio>
using namespace std;
int main()
{
	int n,ge,shi,bai,qian,ans;
	cin>>n;
	ge=n%10;
	shi=n/10%10;
	bai=n/100%10;
	qian=n/1000;
	ans=ge+shi+bai+qian;
	cout<<ans;
	return 0;
}

Pascal :

var
a,b,c,d,e:integer;
begin
read(a);
b:=a div 1000;
c:=a div 100 mod 10;
d:=a div 10 mod 10;
e:=a mod 10;
write(b+c+d+e);
end.