#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
int main(){
    ll a,b,c,d,e;
    cin >> a >> b >> c >> d >> e;
    ll nin = b - c;
    ll res = 0;
    ll pre = 0;
    for(int i = 1;i <= a * nin;i++){
        if(i == 1)res += d,pre = d;
        else if(i % 10 != 0)res += pre;
        else if(e <= pre)res += pre - e,pre = pre - e;
        else res += pre;
    }
    cout << res << endl;
}