public class Sum {

	public static void main(String[] args) {
	
	
		int n;
		int s;
		int i;
		
		
		n = 4;
		s = 0;
		i = 1;
		
		
		while(i <=n) {
		   s = s + i;
		   i = i + 1;
		}
		
		System.out.println(s);
	}
}