#include <bits/stdc++.h>
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define rrep(i, n) for (int i = (int)(n - 1); i >= 0; i--)
#define all(x) (x).begin(), (x).end()
#define sz(x) int(x.size())
#define yn(joken) cout<<((joken) ? "Yes" : "No")<<"\n"
#define YN(joken) cout<<((joken) ? "YES" : "NO")<<"\n"
using namespace std;
using ll = long long;
using vi = vector<int>;
using vl = vector<ll>;
using vs = vector<string>;
using vc = vector<char>;
using vd = vector<double>;
using vvi = vector<vector<int>>;
using vvl = vector<vector<ll>>;
using vvd = vector<vector<double>>;
using vvvl = vector<vector<vector<ll>>>;
const int INF = 1e9;
const ll LINF = 1e18;
template <class T>
bool chmax(T& a, const T& b) {
    if (a < b) {
        a = b;
        return 1;
    }
    return 0;
}
template <class T>
bool chmin(T& a, const T& b) {
    if (b < a) {
        a = b;
        return 1;
    }
    return 0;
}
template <class T>
vector<T> make_vec(size_t a) {
    return vector<T>(a);
}
template <class T, class... Ts>
auto make_vec(size_t a, Ts... ts) {
    return vector<decltype(make_vec<T>(ts...))>(a, make_vec<T>(ts...));
}
template <typename T>
istream& operator>>(istream& is, vector<T>& v) {
    for (int i = 0; i < int(v.size()); i++) {
        is >> v[i];
    }
    return is;
}
template <typename T>
ostream& operator<<(ostream& os, const vector<T>& v) {
    for (int i = 0; i < int(v.size()); i++) {
        os << v[i];
        if (i < int(v.size()) - 1) os << ' ';
    }
    return os;
}

int main(){
    cin.tie(nullptr);
    ios::sync_with_stdio(false);

    int A,B,C,D,E;
    cin>>A>>B>>C>>D>>E;
    int ans=0,last=-1;
    rep(i,A*(B-C)){
        if(last==-1){
            ans+=D;
            last=D;
        }
        else{
            if((i+1)%10==0){
                if(E<=last){
                    ans+=last-E;
                    last-=E;
                }
                else{
                    ans+=last;
                }
            }
            else{
                ans+=last;
            }
        }
    }
    cout<<ans<<endl;
}