#include <iostream>
#include <vector>
#include <map>
#include<string>
#define ll long long
using namespace std;
int main() {
    int a,b,c,d,e,cnt;
    int ans=0;
    cin>>a>>b>>c>>d>>e;
    int cost=d;
    cnt=(b-c)*a;
    if(cnt==1 or cnt==0) ans=cnt*d;
    else {
        ans+=d;
        for (int i=2;i<=cnt;i++){
            if(i%10!=0) {
                 ans+=cost;
            }
            else if(i%10==0 and e<=cost) {
                cost-=e; ans+=cost;
            }
            else if(i%10==0 and e>cost){
              ans+=cost;
            }
        }
    }
    cout<<ans<<endl;
   
        return 0;
}