C :

#include <stdio.h>

int main(){
   int i,s = 0,n;
   scanf("%d",&n);
   for(i = 1;i <= n;i++){
      s = s + i;
   }
   
   printf("%d\n",s);
   return 0;
}

C++ :

#include <iostream>
using namespace std; 
 
int main(){
   int i,s = 0,n;
   cin>>n;
   for(i = 1;i <= n;i++){
      s = s + i;
   }
    
   cout<<s<<endl;
   return 0;
}

Pascal :

var
  x,y:longint;
begin
  readln(x);
  y:=(1+x)*x div 2;
  writeln(y);
end.

Java :

import java.util.*;
public class Main{
	public static void main(String args[]){
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int sum = 0;
		for(int i = 1;i <= n;i++){
			sum+=i;
		}
		System.out.println(sum);		
	}
}

Python :

n =  int(input());
s = 0;
for i in range(1,n + 1):
    s = s + i;
print(s);