#include <bits/stdc++.h>
#define rep(i,n) for(int i = 0; i < (n); i++)
using namespace std;
typedef long long ll;

int main(){
    cin.tie(0);
    ios::sync_with_stdio(0);
    
    int A,B,C,D,E; cin >> A >> B >> C >> D >> E;
    int N = (B - C) * A;
    vector<int> a;
    while(int(a.size()) < N) {
        if(a.empty()) a.push_back(D);
        else {
            int X = a.back();
            if(int(a.size()) % 10 != 0) a.push_back(X);
            else {
                if(E <= X) a.push_back(X - E);
                else a.push_back(X);
            }
        }
    }

    cout << accumulate(a.begin(), a.end(), 0) << endl;
}