C :

#include<stdio.h>
main()
{
	int n,sum = 0;
	scanf("%d",&n);
	while(n > 0)
	{
		sum = sum + n;
		scanf("%d",&n);
	}
	printf("%d",sum);
	return 0;
}

Java :

import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner sc=new Scanner(System.in);
		int s=0,temp;
		while(sc.hasNext()){
			temp=sc.nextInt();
			if(temp<0||temp==0){
				break;
			}
			s+=temp;
		}
		System.out.println(s);
		sc.close();
	}
}