C :

#include<stdio.h>
int main(){
	int i,j,n;
	scanf("%d",&n);
	for(i=1;i<=n;i++){
		for(j=1;j<=n-i;j++){
			printf("*");
		}
		for(j=1;j<=2*i-1;j++){
			printf("@");
		}
		for(j=1;j<=n-i;j++){
			printf("*");
		}
		printf("\n");
	}

	return 0;
}

C++ :

#include <iostream>
using namespace std;

int main(){
	int i,j,n;
	cin>>n;
	for(i = 1;i <= n;i++){
		for(j = 1;j <= n - i;j++) cout<<"*";
		for(j = 1;j <= 2 * i - 1;j++) cout<<"@";
		for(j = 1;j <= n - i;j++) cout<<"*";
		cout<<endl;
	}
}

Java :

import java.util.Scanner;

public class Main {
	public static void main(String[] args) {	
		Scanner sc= new Scanner(System.in);
		int a = sc.nextInt();
		sc.close();
		for(int i=1;i<=a;i++) {
			for(int j=1;j<=a-i;j++) {
				System.out.print("*");
			}
			for(int k=1;k<=i*2-1;k++) {
				System.out.print("@");
			}
			for(int j=1;j<=a-i;j++) {
				System.out.print("*");
			}
			System.out.println();
		}
		
	}
}

Python :

n = int(input())
for i in range(1, n + 1):
    for j in range(1, n - i + 1):
        print("*", end='')
    for j in range(1, 2 * i):
        print('@', end='')
    for j in range(1, n - i + 1):
        print("*", end='')
    print()