Sum of first n natural numbers

Sum of First n natural numbers.

#include<stdio.h>

#include<stdio.h>

int sum(int)

{

     Int s=0,i=1;

     while(i<=n)

         {

             s=s+I;

              I=i+1;

                     }

                      return(s);

                  }

                    Void main()

                     {

                            Int k,s;

                            printf(“Enter the required no:”);

                            k=sum(5);

                            printf(“%d”,k);

                            getch();

                              }

Output: 15