#include <iostream>
#include <map>
#include <cmath>
#include <queue>
#include <vector>
#include <string>
#include <algorithm>
#include <functional>
using namespace std;
#pragma warning (disable: 4996)

int A, B, C, D, E;
int Sum = 0;

int main() {
	cin >> A >> B >> C >> D >> E;

	int pre = D;
	for (int i = 1; i <= A * (B - C); i++) {
		int nex = pre;
		if (i % 10 == 0) {
			if (E <= pre) nex = pre - E;
			else nex = pre;
		}
		Sum += nex;
		pre = nex;
	}
	cout << Sum << endl;
	return 0;
}