/* package whatever; // don't place package name! */
 
import java.util.*;
import java.lang.*;
import java.io.*;
 
/* Name of the class has to be "Main" only if the class is public. */
class Ideone
{
	public static void main (String[] args) throws java.lang.Exception
	{
		// your code goes here
		int k = 3;
		int arr[] = {1,2,3,4,1,2,-3};
		int n = arr.length;
		int count = 0;
		for(int i = 0;i<n;i++){
			for(int j =i+1;j<n;j++){
				if(arr[i] + arr[j] == k){
					count++;
				}
			}
		}
 
		System.out.println(count);
 
	}
}

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