#include<bits/stdc++.h>
using namespace std;
//#define int long long
#define REP(i,m,n) for(int i=(m);i<(n);i++)
#define rep(i,n) REP(i,0,n)
#define pb push_back
#define all(a) a.begin(),a.end()
#define rall(c) (c).rbegin(),(c).rend()
#define mp make_pair
#define endl '\n'
#define vec vector<ll>
#define mat vector<vector<ll> >
#define fi first
#define se second
#define double long double
typedef long long ll;
typedef unsigned long long ull;
typedef pair<ll,ll> pll;
//typedef long double ld;
typedef complex<double> Complex;
const ll INF=1e9+7;
const ll MOD=998244353;
const ll inf=INF*INF;
const ll mod=MOD;
const ll MAX=2000010;



signed main(){
    ll a,b,c,d,e;cin>>a>>b>>c>>d>>e;
    ll k=(b-c)*a;
    ll ans=0;
    ll x=0;
    ll i=1;
    while(i<=k){
        if(i==1){
            ans+=d;
            x=d;
            i++;
            continue;
        }
        if(i%10){
            ans+=x;
        }else{
            if(e<=x){
                ans+=x-e;
                x=x-e;
            }else{
                ans+=x;
            }
        }
        i++;
    }
    cout<<ans<<endl;
}