C++ :

#include<iostream>
using namespace std;
int a[10100];
int main()
{
    int n;
    int i,j;
    int temp,sum=0;
 
    cin>>n;
    for(i=1;i<=n;i++)
        cin>>a[i];
    for(i=1;i<=n;i++)
        for(j=i+1;j<=n;j++)
            if(a[i]>a[j])
            {
                temp=a[i];
                a[i]=a[j];
                a[j]=temp;
                sum++;
            }
    cout<<sum<<endl;
    return 0;
}

Pascal :

var a,r:array[1..100000] of longint;
    i,j,n,k,sum:longint;
procedure mergesort(st,ed:longint);
var mid:longint;
begin
  if st=ed then exit;
  mid:=(st+ed) div 2;
  mergesort(st,mid);
  mergesort(mid+1,ed);
  i:=st; j:=mid+1; k:=st;
  while (i<=mid) and (j<=ed) do
  begin
    if a[i]<=a[j] then begin r[k]:=a[i]; inc(i); inc(k); end
      else begin sum:=sum+mid+1-i; r[k]:=a[j]; inc(j); inc(k); end;
  end;
  while i<=mid do begin r[k]:=a[i]; inc(i); inc(k); end;
  while j<=ed do begin r[k]:=a[j]; inc(j); inc(k); end;
  for i:=st to ed do a[i]:=r[i];
end;
begin
  readln(n);
  for i:=1 to n do
    read(a[i]);
  mergesort(1,n);
  writeln(sum);
end.

Java :

import java.util.Scanner;

public class Main {
	public static long count = 0;
	public static void main(String[] args) {
		Scanner input = new Scanner(System.in);
		int n = input.nextInt();
		int[] array = new int[n];
		for (int i = 0; i < n; i++) {
			array[i] = input.nextInt();
		}
		mergesort(array, 0, n - 1);
		System.out.println(count);
	}

	private static void mergesort(int[] array, int start, int end) {
		if (start >= end)
			return;
		int mid = start + (end - start) / 2;
		mergesort(array,start,mid);
		mergesort(array,mid+1,end);
		merge(array,start,mid,end);
	}

	private static void merge(int[] array, int start, int mid, int end) {
		int[] num = new int[end-start+1];
		int p = start;
		int q = mid+1; 
		int index = 0;
		while(p<=mid&&q<=end) {
			if(array[p]>array[q]) {
				count += mid-p+1;
				num[index++] = array[q++];
			}else {
				num[index++] = array[p++];				
			}
		}
		while(p<=mid) {
			num[index++] = array[p++];
		}
		while(q<=end) {
			num[index++] = array[q++];
		}
		System.arraycopy(num, 0, array, start, end-start+1);
 	}
}