#include <stdio.h>

int main() {
    int n;
    printf("enter a no. \n");
    scanf("%d \n",&n);
    
    int sum=0;
    int i;
    for (i=1;i<=n;i++)
    { 
        sum = sum + i;
        
    }
    printf("sum is : %d",sum);
    return 0;
}