C++ :

#include<iostream>

using namespace std;

int main()
{
	int a,b,c;
	cin>>a;
	c=0;
	while (a!=0)
	{
		b=a%10;
		c=c+b;
		a=a/10;
	}
	cout<<c<<endl;
	return 0;
}

Pascal :

var a,b,c:longint;
begin
  readln(a);
  c:=0;
  while a<>0 do
        begin
          b:=a mod 10;
          c:=c+b;
          a:=a div 10;
        end;
  writeln(c);
end.