#include <stdio.h>
#include <stdlib.h>

int main(void) {
	int a;
	long int fuel, result = 0;
	while ((scanf("%d\n", &a) > 0)) {
		fuel = (a / 3) - 2;
		while (fuel > 0) {
			result += fuel;
			fuel = (fuel / 3) - 2;
		}
	}
	printf("%lu\n", result);
	return result != 5139037;
}