C++ :

#include<iostream>
#include<cstdio>
using namespace std;
int main()
{
long long i,j,n,z,first=0;
cin>>n;
for(i=2;i<=n;++i)
{
z=i;
for(j=1;j<i/2+1;++j)
if(i%j==0)
z-=j; 
if(z==0)
{cout<<i<<endl;
first=1;
}
}
if(first==0)
cout<<"No";
return 0;
}

Java :

import java.util.Scanner;
//import java.util.ArrayList;

class  Main
{
	public static void main(String[] args) 
	{
        Scanner in =new Scanner(System.in);

		int a=in.nextInt();

		wanshu(a);

	}
	
    public static void wanshu(int a)
	{
		int Sum=0;
		for(int b=2;b<=a;b++)
		{
			int sum=0;
			for(int i=1;i<=b/2;i++)
			{
				if(b%i==0)
					sum=sum+i;
			}
			if(sum==b)
			{
				System.out.println(b);
				Sum++;
			}
		}

		if(Sum==0)
			System.out.println("No");
			
	}



}