A - Crne [O(n)]

/*
user: hasib
*/
#include<stdio.h>
int main()
{
    int n, half;
    int i;
    int maxResult = -1; //initializing with a very small value;

    scanf("%d", &n);
    half = n/2;

    for(i=0; i<=half; i++)
    {
        if(maxResult < (i+1)*(n-i+1) )
        {
            maxResult = (i+1)*(n-i+1);
        }
    }

    printf("%d\n", maxResult);

}