#include <iostream>
#include <vector>
#include <stdio.h>

using namespace std;

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

	int num = A * (B - C);

	int step = num / 10;

	long long ans = 0;
	if (num < 10) {
		cout << num * D << endl;
		return 0;
	}
	else {
		ans += 9 * D;
	}
	for (int i = 1; i < step; i++) {
		ans += 10 * max((D - E * i), (D % E));
	}


	ans += (num % 10+1) * max((D - E * step), D % E);

	cout << ans << endl;
}