#include <algorithm>
#include <bitset>
#include <cassert>
#include <cctype>
#include <cmath>
#include <cstdio>
#include <ctime>
#include <fstream>
#include <functional>
#include <iomanip>
#include <ios>
#include <iostream>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <unordered_map>
#include <vector>
using namespace std;
using ll = long long;
#define REP(i, a) for (int i = 0; i < (a); ++i)
#define FOR(i, a, b) for (int i = (a); i < (b); ++i)
#define FORR(i, a, b) for (int i = (a)-1; i >= (b); --i)
#define ALL(obj) (obj).begin(), (obj).end()
#define SIZE(obj) (int)(obj).sizeT()
#define YESNO(cond, yes, no) \
{ cout << ((cond) ? (yes) : (no)) << endl; }
#define SORT(list) sort(ALL((list)));
#define RSORT(list) sort((list).rbegin(), (list).rend())
#define ASSERT(cond, mes) assert(cond&& mes)
constexpr int MOD = 1'000'000'007;
constexpr int INF = 1'050'000'000;
template <typename T>
T round_up(const T& a, const T& b) {
return (a + (b - 1)) / b;
}
template <typename T1, typename T2>
istream& operator>>(istream& is, pair<T1, T2>& p) {
is >> p.first >> p.second;
return is;
}
template <typename T1, typename T2>
ostream& operator<<(ostream& os, pair<T1, T2>& p) {
os << p.first << p.second;
return os;
}
template <typename T>
istream& operator>>(istream& is, vector<T>& v) {
REP(i, (int)v.size())
is >> v[i];
return is;
}
template <typename T>
T clamp(T& n, T a, T b) {
if (n < a) n = a;
if (n > b) n = b;
return n;
}
template <typename T>
static T GCD(T u, T v) {
T r;
while (v != 0) {
r = u % v;
u = v;
v = r;
}
return u;
}
template <typename T>
static T LCM(T u, T v) {
return u / GCD(u, v) * v;
}
template <typename T>
std::vector<T> enum_div(T n) {
std::vector<T> ret;
for (T i = 1; i * i <= n; ++i) {
if (n % i == 0) {
ret.push_back(i);
if (i * i != n) { ret.push_back(n / i); }
}
}
return ret;
}
template <typename T>
bool chmin(T& a, const T& b) {
if (a > b) {
a = b;
return true;
}
return false;
}
template <typename T>
bool chmax(T& a, const T& b) {
if (a < b) {
a = b;
return true;
}
return false;
}
struct ToUpper {
char operator()(char c) {
return toupper(c);
}
};
struct ToLower {
char operator()(char c) {
return tolower(c);
}
};
int main() {
cin.tie(0);
ios::sync_with_stdio(false);
cout << fixed << setprecision(20);
int T, A, B, C, D;
cin >> T >> A >> B >> C >> D;
int ans = 0;
if (T >= C) {
ans += D;
T -= C;
}
if (T >= A) { ans += B; }
cout << ans << endl;
return 0;
}