Language: C++

#include <bits/stdc++.h>
using namespace std;

// 変数ダンプ先。coutかcerr
#define DUMPOUT cerr

// 提出時はコメントアウト
#define DEBUG_

// #define int long long // intで書いたけど心配なときにlong longに変換する
struct Fast {Fast(){std::cin.tie(0);ios::sync_with_stdio(false);}} fast;

/* cpp template {{{ */

/* short */
#define pb push_back
#define eb emplace_back
#define mp make_pair
#define Fi first
#define Se second
#define ALL(v) begin(v), end(v)
#define RALL(v) rbegin(v), rend(v)
#define X real()
#define Y imag()

/* REPmacro */
#define REPS(i, a, n) for (ll i = (a); i < (ll)(n); ++i)
#define REP(i, n) REPS(i, 0, n)
#define RREP(i, n) REPS(i, 1, n + 1)
#define DEPS(i, a, n) for (ll i = (a); i >= (ll)(n); --i)
#define DEP(i, n) DEPS(i, n, 0)
#define EACH(i, n) for (auto&& i : n)

/* debug */
#define debug(x) cerr << x << " " << "(L:" << __LINE__ << ")" << '\n';

/* alias */
using ll = long long;
using ull = unsigned long long;
using vi = vector<int>;
using vvi = vector<vi>;
using vvvi = vector<vvi>;
using pii = pair<int, int>;
using D = double;
using P = complex<D>;
using vs = vector<string>;
template <typename T> using PQ = priority_queue<T>;
template <typename T> using minPQ = priority_queue<T, vector<T>, greater<T>>;

/* const */
const int INF = 1001001001;
const ll LINF = 1001001001001001001ll;
const int MOD = 1e9 + 7;
const D EPS = 1e-9;
const int dx[] = {0, 1, 0, -1, 1, -1, 1, -1}, dy[] = {1, 0, -1, 0, 1, -1, -1, 1};

/* func */
inline bool inside(int y, int x, int H, int W) {return y >= 0 && x >= 0 && y < H && x < W;}
inline int in() {int x; cin >> x; return x;}
inline ll IN() {ll x; cin >> x; return x;}
inline vs split(const string& t, char c) {vs v; stringstream s(t); string b; while(getline(s, b, c)) v.eb(b); return v;}
template <typename T> inline bool chmin(T& a, const T& b) {if (a > b) a = b; return a > b;}
template <typename T> inline bool chmax(T& a, const T& b) {if (a < b) a = b; return a < b;}
template <typename T, typename S> inline void print(const pair<T, S>& p) {cout << p.first << " " << p.second << endl;}
template <typename T> inline void print(const T& x) {cout << x << '\n';}
template <typename T, typename S> inline void print(const vector<pair<T, S>>& v) {for (auto&& p : v) print(p);}
template <typename T> inline void print(const vector<T>& v, string s = " ") {REP(i, v.size()) cout << v[i] << (i != (ll)v.size() - 1 ? s : "\n");}
// clang-format on
/* }}} */

#ifdef DEBUG_
#define DEB
#else
// DEB と打つとデバッグ時以外はコメントアウトになる
#define DEB /##/
#endif

// 変数ダンプ用マクロ。デバッグ時以外は消滅する
// 引数はいくつでもどんな型でも可（ストリーム出力演算子があればOK）
#define dump(...) DEB DUMPOUT<<"  "; \
DUMPOUT<<#__VA_ARGS__<<" :["<<__LINE__<<":"<<__FUNCTION__<<"]"<<endl; \
DUMPOUT<<"    "; \
dump_func(__VA_ARGS__)

// デバッグ用変数ダンプ関数
void dump_func() {
    DUMPOUT << endl;
}
template <class Head, class... Tail>
void dump_func(Head&& head, Tail&&... tail)
{
    DUMPOUT << head;
    if (sizeof...(Tail) == 0) {
        DUMPOUT << " ";
    }
    else {
        DUMPOUT << ", ";
    }
    dump_func(std::move(tail)...);
}

// vector出力
template<typename T>
ostream& operator << (ostream& os, vector<T>& vec) {
    os << "{";
    for (int i = 0; i<vec.size(); i++) {
        os << vec[i] << (i + 1 == vec.size() ? "" : ", ");
    }
    os << "}";
    return os;
}

signed main() {
    int N, K, X, Y; cin >> N >> K >> X >> Y;
    ll ans;
    ans = N * X;
    if (K < N) {
        ans -= (N - K) * (X - Y);
    }
    cout << ans << endl;

    cout << N * (N + 1) / 2 << endl;

    return 0;
}

// https://github.com/kurokoji/.cpp-Template/wiki テンプレートについて
// http://www.creativ.xyz/dump-cpp-652 dump()について
// https://gist.github.com/rigibun/7905920 色々

Compiler output:
a.cc: In function 'int main()':
a.cc:23:15: warning: empty parentheses were disambiguated as a function declaration [-Wvexing-parse]
   23 | #define X real()
      |               ^~
a.cc:114:15: note: in expansion of macro 'X'
  114 |     int N, K, X, Y; cin >> N >> K >> X >> Y;
      |               ^
a.cc:23:15: note: remove parentheses to default-initialize a variable
   23 | #define X real()
      |               ^~
a.cc:114:15: note: in expansion of macro 'X'
  114 |     int N, K, X, Y; cin >> N >> K >> X >> Y;
      |               ^
a.cc:23:15: note: or replace parentheses with braces to value-initialize a variable
   23 | #define X real()
      |               ^~
a.cc:114:15: note: in expansion of macro 'X'
  114 |     int N, K, X, Y; cin >> N >> K >> X >> Y;
      |               ^
a.cc:24:15: warning: empty parentheses were disambiguated as a function declaration [-Wvexing-parse]
   24 | #define Y imag()
      |               ^~
a.cc:114:18: note: in expansion of macro 'Y'
  114 |     int N, K, X, Y; cin >> N >> K >> X >> Y;
      |                  ^
a.cc:24:15: note: remove parentheses to default-initialize a variable
   24 | #define Y imag()
      |               ^~
a.cc:114:18: note: in expansion of macro 'Y'
  114 |     int N, K, X, Y; cin >> N >> K >> X >> Y;
      |                  ^
a.cc:24:15: note: or replace parentheses with braces to value-initialize a variable
   24 | #define Y imag()
      |               ^~
a.cc:114:18: note: in expansion of macro 'Y'
  114 |     int N, K, X, Y; cin >> N >> K >> X >> Y;
      |                  ^
a.cc:114:35: error: no match for 'operator>>' (operand types are 'std::basic_istream<char>::__istream_type' {aka 'std::basic_istream<char>'} and 'int')
  114 |     int N, K, X, Y; cin >> N >> K >> X >> Y;
      |                     ~~~~~~~~~~~~~ ^~
      |                              |
      |                              std::basic_istream<char>::__istream_type {aka std::basic_istream<char>}
In file included from /usr/include/c++/14/sstream:40,
                 from /usr/include/c++/14/complex:45,
                 from /usr/include/c++/14/ccomplex:39,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:127,
                 from a.cc:1:
/usr/include/c++/14/istream:170:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(bool&) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>]' (near match)
  170 |       operator>>(bool& __n)
      |       ^~~~~~~~
/usr/include/c++/14/istream:170:7: note:   conversion of argument 1 would be ill-formed:
a.cc:23:15: error: cannot bind non-const lvalue reference of type 'bool&' to a value of type 'int'
   23 | #define X real()
      |           ~~~~^~
a.cc:114:38: note: in expansion of macro 'X'
  114 |     int N, K, X, Y; cin >> N >> K >> X >> Y;
      |                                      ^
/usr/include/c++/14/istream:174:7: note: candidate: 'std::basic_istream<_CharT, _Traits>& std::basic_istream<_CharT, _Traits>::operator>>(short int&) [with _CharT = char; _Traits = std::char_traits<char>]' (near match)
  174 |       operator>>(short& __n);
      |       ^~~~~~~~
/usr/include/c++/14/istream:174:7: note:   conversion of argument 1 would be ill-formed:
a.cc:23:15: error: cannot bind non-const lvalue reference of type 'short int&' to a value of type 'int'
   23 | #define X real()
      |           ~~~~^~
a.cc:114:38: note: in expansion of macro 'X'
  114 |     int N, K, X, Y; cin >> N >> K >> X >> Y;
      |                                      ^
/usr/include/c++/14/istream:177:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(short unsigned int&) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>]' (near match)
  177 |       operator>>(unsigned short& __n)
      |       ^~~~~~~~
/usr/include/c++/14/istream:177:7: note:   conversion of argument 1 would be ill-formed:
a.cc:23:15: error: cannot bind non-const lvalue reference of type 'short unsigned int&' to a value of type 'int'
   23 | #define X real()
      |           ~~~~^~
a.cc:114:38: note: in expansion of macro 'X'
  114 |     int N, K, X, Y; cin >> N >> K >> X >> Y;
      |                                      ^
/usr/include/c++/14/istream:181:7: note: candidate: 'std::basic_istream<_CharT, _Traits>& std::basic_istream<_CharT, _Traits>::operator>>(int&) [with _CharT = char; _Traits = std::char_traits<char>]' (near match)
  181 |       operator>>(int& __n);
      |       ^~~~~~~~
/usr/include/c++/14/istream:181:7: note:   conversion of argument 1 would be ill-formed:
a.cc:23:15: error: cannot bind non-const lvalue reference of type 'int&' to an rvalue of type 'int'
   23 | #define X real()
      |           ~~~~^~
a.cc:114:38: note: in expansion of macro 'X'
  114 |     int N, K, X, Y; cin >> N >> K >> X >> Y;
      |                                      ^
/usr/include/c++/14/istream:184:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(unsigned int&) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>]' (near match)
  184 |       operator>>(unsigned int& __n)
      |       ^~~~~~~~
/usr/include/c++/14/istream:184:7: note:   conversion of argument 1 would be ill-formed:
a.cc:23:15: error: cannot bind non-const lvalue reference of type 'unsigned int&' to a value of type 'int'
   23 | #define X real()
      |           ~~~~^~
a.cc:114:38: note: in expansion of macro 'X'
  114 |     int N, K, X, Y; cin >> N >> K >> X >> Y;
      |                                      ^
/usr/include/c++/14/istream:188:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(long int&) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>]' (near match)
  188 |       operator>>(long& __n)
      |       ^~~~~~~~
/usr/include/c++/14/istream:188:7: note:   conversion of argument 1 would be ill-formed:
a.cc:23:15: error: cannot bind non-const lvalue reference of type 'long int&' to a value of type 'int'
   23 | #define X real()
      |           ~~~~^~
a.cc:114:38: note: in expansion of macro 'X'
  114 |     int N, K, X, Y; cin >> N >> K >> X >> Y;
      |                                      ^
/usr/include/c++/14/istream:192:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(long unsigned int&) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>]' (near match)
  192 |       operator>>(unsigned long& __n)
      |       ^~~~~~~~
/usr/include/c++/14/istream:192:7: note:   conversion of argument 1 would be ill-formed:
a.cc:23:15: error: cannot bind non-const lvalue reference of type 'long unsigned int&' to a value of type 'int'
   23 | #define X real()
      |           ~~~~^~
a.cc:114:38: note: in expansion of macro 'X'
  114 |     int N, K, X, Y; cin >> N >> K >> X >> Y;
      |                                      ^
/usr/include/c++/14/istream:199:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(long long int&) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>]' (near match)
  199 |       operator>>(long long& __n)
      |       ^~~~~~~~
/usr/include/c++/14/istream:199:7: note:   conversion of argument 1 would be ill-formed:
a.cc:23:15: error: cannot bind non-const lvalue reference of type 'long long int&' to a value of type 'int'
   23 | #define X real()
      |           ~~~~^~
a.cc:114:38: note: in expansion of macro 'X'
  114 |     int N, K, X, Y; cin >> N >> K >> X >> Y;
      |                                      ^
/usr/include/c++/14/istream:203:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(long long unsigned int&) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>]' (near match)
  203 |       operator>>(unsigned long long& __n)
      |       ^~~~~~~~
/usr/include/c++/14/istream:203:7: note:   conversion of argument 1 would be ill-formed:
a.cc:23:15: error: cannot bind non-const lvalue reference of type 'long long unsigned int&' to a value of type 'int'
   23 | #define X real()
      |           ~~~~^~
a.cc:114:38: note: in expansion of macro 'X'
  114 |     int N, K, X, Y; cin >> N >> K >> X >> Y;
      |                                      ^
/usr/include/c++/14/istream:219:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(float&) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>]' (near match)
  219 |       operator>>(float& __f)
      |       ^~~~~~~~
/usr/include/c++/14/istream:219:7: note:   conversion of argument 1 would be ill-formed:
a.cc:23:15: error: cannot bind non-const lvalue reference of type 'float&' to a value of type 'int'
   23 | #define X real()
      |           ~~~~^~
a.cc:114:38: note: in expansion of macro 'X'
  114 |     int N, K, X, Y; cin >> N >> K >> X >> Y;
      |                                      ^
/usr/include/c++/14/istream:223:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(double&) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>]' (near match)
  223 |       operator>>(double& __f)
      |       ^~~~~~~~
/usr/include/c++/14/istream:223:7: note:   conversion of argument 1 would be ill-formed:
a.cc:23:15: error: cannot bind non-const lvalue reference of type 'double&' to a value of type 'int'
   23 | #define X real()
      |           ~~~~^~
a.cc:114:38: note: in expansion of macro 'X'
  114 |     int N, K, X, Y; cin >> N >> K >> X >> Y;
      |                                      ^
/usr/include/c++/14/istream:227:7: note: ca