[二分] L. Berland University CFcontest/1090/L

#include <bits/stdc++.h>
#define ll long long
using namespace std;
ll t, n, a, b, k;
ll w1, w2;

bool check(ll x)
{
	ll p = min(x, a), q = min(x, b);
	ll sz = p * w1 + q * w2;	// 最多上的课 x人总数
	return sz >= x * k;
}

int main()
{
	scanf("%lld %lld %lld %lld %lld", &t, &n, &a, &b, &k);
	w1 = (n + 1) / 2, w2 = n / 2;
	
	ll ans = 0;
	ll l = 0, r = t;
	while (l <= r)	// 二分可通过人数
	{
		ll mid = (l + r) / 2;
		if (check(mid))
		{
			ans = mid;
			l = mid + 1;
		}
		else 
			r = mid - 1;
	}
	printf("%lld\n", ans);
	
	return 0;
}