D.cpp

/*
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         ,-;    \---)_\ ,','/
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         (_`     ---'" ,-')
         / `--.__,. ,-'    \
-hrr-    )-.__,-- ||___,--' `-.
        /._______,|__________,'\
        `--.____,'|_________,-'

                             __
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   /        (____)(----. )       ,'
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 |         ,'      `--.      -,\ |
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    \    ,'   `-.     ,'_,-'    \
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    \       /  // ,'|      ,--'  `-.
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       ,-'              |               /
      /                 |             -'

*/

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp> // Common file
#include <ext/pb_ds/tree_policy.hpp> // Including 

using namespace __gnu_pbds;
using namespace std;


typedef long long int ll;
typedef pair<int, int> pi;
typedef pair<ll, ll> pl;
typedef vector<int> vi;
typedef vector<ll> vl;
typedef vector<vi> vvi;
typedef vector<vl> vvl;
typedef vector<pi> vpi;
typedef vector<pl> vpl;
typedef vector<vpi> vvpi;
typedef vector<vpl> vvpl;
typedef set<int> si;
typedef multiset<int> msi;
typedef set<ll> sl;
typedef multiset<ll> msl;
typedef tree<
int,
null_type,
less<int>,
rb_tree_tag,
tree_order_statistics_node_update>
ordered_set;

template<class T> using func = function<T>;

#define clrcin cin.ignore(numeric_limits<streamsize>::max(),'\n');
#define GOGOGO ios::sync_with_stdio(false); cin.tie(nullptr);
#define BYEBYE return 0;

#define all(cn) (cn).begin(), (cn).end()
#define rep(i, n) for (int i = 0; i < n; ++i)
#define repk(i, k, n) for(int i = k; i < n; ++i)

#define mp make_pair
#define pb push_back
#define fi first
#define se second

#define popcnt __builtin_popcount
#define gcd std::__detail::__gcd
#define lcm std::__detail::__lcm

const int INFI = 1e9 + 5;
const ll INFL = 4e18 + 5;

template<class T> void aread(T* arr, int ___n)
{
    rep(i, ___n)
    {
        cin >> arr[i];
    }
}


// LIORZ LIORZ LIORZ LIORZ LIORZ


































const int maxn =1e5 + 5;
//#define BRUH_WHY_TESTCASES

void solve()
{
    ll d, k, a , b, t; cin >> d >> k >> a >> b >> t;
    ll always = min(k, d) * a;
    ll left = max(0LL, d - k);
    ll part2 = (left / k) * min(t+a*k, k * b);
    left %= k;
    ll part3 = min(t+a*left, b*left);
    cout << always + part2 + part3 << '\n';
    // k with t + a*k
    // 1 with b



}










































int main()
{
    GOGOGO
    int t=1;
    #ifdef BRUH_WHY_TESTCASES
        cin >> t;
    #endif
    while(t--)
    {
        solve();
    }
    BYEBYE
}

/* PLEASE READ THIS
* N = 1
* GUESS A!!!!!!!
* DO SOMETHING INSTEAD OF NOTHING
*/