80分为什么！！

#include<iostream>
using namespace std;
int main()
{
	int x, n;
	int a, b, c, d;
	
	cin >> x >> n;
	b = n % 7;
  
	a = (n - b) / 7;//1
	c = 5 * a + b;
	d = 250 * c;
	cout << d << endl;
	return 0;
}