#include <cstdio>
#include <cstring>
#include <iostream>
#include <string>
#include <cmath>
#include <bitset>
#include <vector>
#include <map>
#include <set>
#include <queue>
#include <deque>
#include <algorithm>
#include <complex>
#include <unordered_map>
#include <unordered_set>
#include <random>
#include <cassert>
#include <fstream>
#include <utility>
#include <functional>
#include <time.h>
#include <stack>
#include <array>
#include <list>
#include <atcoder/all>
#define popcount __builtin_popcount
using namespace std;
using namespace atcoder;
typedef long long ll;
typedef pair<int, int> P;

int main()
{
    int a, b, c, d, e;
    cin>>a>>b>>c>>d>>e;
    int ans=0;
    int x=d;
    for(int i=1; i<=a*(b-c); i++){
        if(i==1) ans+=d;
        else if(i%10!=0) ans+=x;
        else if(e<=x){
            x-=e;
            ans+=x;
        }else{
            ans+=x;
        }
    }
    cout<<ans<<endl;
    return 0;
}