C :

#include <stdio.h>
int main()
{
	int n,a,b,c,d,e,f=0;
	scanf("%d", &n);
	for (a=1;a<=n;a++)
	{
		for (b=a+1;b<=n;b++)
		{
			c=a+b;
			d=c%3;
			e=c%7;
			if (d==0||e==0)
			f++;
		}
	}
	printf("%d",f);
	return 0;
}

C++ :

#include <iostream>
#include <iomanip>
#include <cmath>

using namespace std;

int main(){
    int n;
    cin>>n;
    int i,j,s=0;
    for(i=1;i<n;i++){
    	for(j=i+1;j<=n;j++){
    		if((i+j)%3==0||(i+j)%7==0){
    			s=s+1;
			}
		}
	}cout<<s<<endl;
}

Pascal :

var i,j,n,s:integer;
begin
    readln(n);
    for i := 1 to n do
       for j := i + 1 to n do
         if ((i + j) mod 3 = 0) or  ((i + j) mod 7 = 0) then
           s := s + 1 ;
  writeln(s);
  readln;
end.

Java :

import java.util.Scanner;
public class Main{
	public static void main(String[] args) {
		Scanner scanner=new Scanner(System.in);
		int n=scanner.nextInt();
		int num=0;
		for(int i=1;i<=n;i++){
			for(int j=i;j<=n;j++){
				if(((i+j)%3==0||(i+j)%7==0)&&(i!=j)){
					num++;
				}
			}
		}
		System.out.println(num);	
	}
}

Python :

n = int(input());
i = 0
x = 0
s = 0
for i in range(1,n+1):
    for x in range(i,n +1):
        if i != x:
            if (i + x) % 3 == 0 or (i + x) % 7 == 0:
                s += 1
print(s)