#include <iostream> #include <vector> #include <iomanip> #include <algorithm> #include <map> #include <cmath> #include <bitset> #include <string> #include <queue> #include <stack> #include <set> using namespace std; int main() { int a, b, c, d, e; cin >> a >> b >> c >> d >> e; int ans = a - b; if (e < d) ans += c * (d - e); cout << ans << endl; }