import java.util.HashMap;

/*

* Two SUM problem using a hash

*/

public class TwoSum {

public static void main(String[] args) {

int[] numbers = Utils.readIntArrayFromFile("data/HashInt.txt");

HashMap<Integer, Integer> table = new HashMap<Integer, Integer>();

for (int i : numbers) {

table.put(i, 1);

}

int count = 0;

for (int sum=2500; sum<=4000; sum++) {

boolean found = false;

for (int index=0; index<numbers.length; index++) {

if (table.containsKey(sum-numbers[index]) && ((sum-numbers[index]) != numbers[index])) {

found = true;

break;

}

}

if (found)

count++;

}

System.out.println(count);

}

}