#include <stdio.h>

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