Challenging program

/****
Question
challenging program for student
Write a program which takes a number(x) and a list of number(numList) as a input and print number of pairs made from numList that are equal to x.After subtraction.

*Test Case*
Input
3 [5,4,6,7,9,8,1,17,14]

Output
5

Pair
4,1
7,4
9,6
8,5
17,14

Input
2 [5,4,6,7,9,8,1,17,14]

Output
4

Pair
6,4
7,5
9,7
8,6

***/

/**
solution by Fahad
**/

#include<stdio.h>
#include<conio.h>
#include<math.h>
int main()
{
    int no,i,j,a,arr[20],temp,count=0;
    printf("\nEnter desire no=");
    scanf("%d",&no);
    printf("\nHow many numbers you want to insert");
    scanf("%d",&a);
    if(a>=20)
    {
        printf("Sorry upto 20 number is accepted");
        return 0;
    }
    for(i=0;i<a;i++)
    {
        printf("\nNo %d=",i+1);
        scanf("%d",&arr[i]);
    }
    printf("\nNumber You enter is :\n");
    for(i=0;i<a;i++)
    {
        printf("\n%d",arr[i]);
    }
    for(i=0;i<a;i++)
    {
        temp=arr[i];
        for(j=i+1;j<a;j++)
        {
            if(abs(temp-arr[j])==no)
            {
                count++;
            }
        }
    }
    printf("\nAfter subtraction of this number we found total %d pair",count);
    return 0;
}