#include <iostream>
#include <algorithm>
#include <cmath>
#include <vector>
#include <string>
#include <iomanip>
#include <functional>
#include <deque>
#include <stack>
#include <queue>
#include <bitset>
#include <map>
#include <set>
#include <unordered_set>
#include <numeric>
#include <array>
using namespace std;
typedef long long ll;
#define rep(i,n) for (ll i = 0; i < (ll)(n); i++)
#define REP(i,n) for (ll i = 1; i <= (ll)(n); i++)
#define FOR(i,a,b) for(ll i=a;i<=b;i++)
#define bit(x,i)(((x)>>(i))&1)
#define all(x) x.begin(),x.end()
#define fcout cout<<fixed<<setprecision(15)
#define PI 3.1415926535897932384626433832795028841971693993751058209749445923078160628620899
const ll INF = 1000000000000000000;
const ll NIL = -1;
const ll MOD = 998244353;
const ll dx[4] = { 0,1,0,-1 };
const ll dy[4] = { 1,0,-1,0 };

ll A, B, C, D, E;

int main(void) {
	cin >> A >> B >> C >> D >> E;
	ll U = (D > E ? C : 0);
	cout << A - B + (D - E) * U << endl;
	return 0;
}