#include <stdio.h>

int main() 
{
    int money = 0;
    scanf("%d", &money);
    int total = money;
    int empty = money;
    
    while (empty >=2)
    {
        total += empty/2;
        empty = empty/2 + empty%2;
    }
    printf("%d\n", total);
	return 0;
}