Shirt - Matching Pairs - C

A shop to increase sales during a festival has an offer that a customer will get a discount if the customer buys shirts having same size in pairs. Any customer who buys will choose N shirts and the size of the shirt is denoted by S(i) where 1 <= i <=N. Two shirts S(i) and S(j) are matching and form a pair only if S(i) = S(j). The program must print the number of pairs eligible for the discount.

Input Format: The first line will contain the value of N The second line will contain the the size of N shirts S(1) to S(N) with each size separated by a space.

Output Format: The first line will contain the number of matching pairs eligible for the discount.

Constraints: 2 <= N <= 100

Example Input/Output 1:

Input: 

9 

10 20 20 10 10 30 44 10 20

Output: 

3

Explanation: The matching pairs are (10,10) (20,20) (10,10).

Example Input/Output 2:

Input: 

6

42 44 40 42 44 42

Output:

2

Explanation: The matching pairs are (42,42) (44,44)

Source Code:  //C

#include<stdio.h>

#include <stdlib.h> 

int main()

{

int r=0,n,c;

scanf("%d",&n);

int a[n],i,b[100];

for(i=0;i<n;i++)

{

scanf("%d",&a[i]);

b[i]=-1;

}

for(i=0;i<n;i++)

{

    c=1;

    for(j=i+1;j<n;j++)

    {

        if(a[i]==a[j])

        {

           c++;

           b[j]=0;

        }

    }

    if(b[i]!=0)

    b[i]=c;

}

for(i=0;i<n;i++)

{

    if(b[i]>1)

    r+=b[i]/2;

}

printf("%d",r);

}

Source code:  //Java
import java.util.*;
public class Hello {

    public static void main(String[] args) {
                        Scanner s=new Scanner(System.in);
                        int n=s.nextInt();
                        int[] a=new int[n];
                        int i,j,d=0;
                        for(i=0;i<n;i++){
                        a[i]=s.nextInt();
                        }
        Arrays.sort(a);
                        for(i=0;i<n-1;i++){
                          if(a[i]==a[i+1]){
                          d++;
                          i++;
                          }
                        }
System.out.println(d);
            }

}