#include<iostream.h>
#include<conio.h>
int main()
{
int n;
int sum(int);
clrscr();
cout<<"Enter the number : ";
cin>>n;
cout<<"Sum of "<<n<<" natural numbers = "<<sum(n);
getch();
return 0;
}
int sum(int n)
{
int s = 0;
if (n == 0)
return(0);
else
s=n+sum(n-1);
return(s);
}