Codeforces-Atcoder/atcoder/abc044/A.cpp at master · nabil0day/Codeforces-Atcoder · GitHub

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/*****
                                                     __Bismillahir Rahmanir Rahim__
                                               American International University Bangladesh (AIUB)
                                                          Hadiur Rahman Nabil


*****/
#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef long double ld;
typedef vector <int> vi;


#define pb push_back
#define mp make_pair
#define gcd(a,b) __gcd(a,b)
#define endl "\n"

const int mod = 1e9 + 7;
const double PI = 3.1415926535897932384626;
const int mod_2 = 998244353;
const int MAX=100005;


int main()
{
        ios_base::sync_with_stdio(false);
        cin.tie(NULL);
        cout.tie(NULL);

ll n,k,x,y;
cin>>n>>k>>x>>y;
if(n<=k)
{
        cout<<n*x<<"\n";
}
else{
        cout<<k*x+(n-k)*y<<endl;
}


return 0;


}