#include<stdio.h>
#include<conio.h>
int main()
{
    int a, sum = 0;
scanf("%d",&a);
    if( a > 0 )
    {
        for ( int i = -1; i <= a; i++)
        sum += i;
    }

    else
    {
        for (int i = 1; i <= -a; i++)
        sum += i;
        sum = 1 - sum;
    }
printf("summa ravna %d",sum);
getch();
}

first:
printf("summa ravna %d",sum);
use just:
printf("%d",sum);

second:
don't use:
getch();

third:
if A>0 sum from 1, not from -1