Sum of n-(n-1)-(n-2)-...4-3-2-1 using C language

#include<stdio.h>
int main()
{
 int a,n,v;
 printf("enter the value of n :");
 scanf("%d",&n);
 v=n;
 for(a=n-1;a>=1;a--)
 {
  v=v-a;
 }
 printf("value=%d",v);
 return 0;
}

Output: