#include <algorithm>
#include <cfloat>
#include <climits>
#include <cmath>
#include <complex>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <functional>
#include <iostream>
#include <map>
#include <memory>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <utility>
#include <vector>

using namespace std;

typedef long long ll;

#define sz size()
#define pb push_back
#define mp make_pair
#define fi first
#define se second
#define all(c) (c).begin(), (c).end()
#define rep(i,a,b) for(ll i=(a);i<(b);++i)
#define per(i,a,b) for(ll i=(b-1);i>=(a);--i)
#define clr(a, b) memset((a), (b) ,sizeof(a))
#define ctos(c) string(1,c)
#define print(x) cout<<#x<<" = "<<x<<endl;

#define MOD 1000000007

int main() {
  ll a,b;
  cin>>a>>b;
  ll n;
  cin>>n;
  map<ll,ll> ma;
  rep(i,0,n){
    ll c;
    cin>>c;
    ma[c]++;
  }
  ll ans = 0;
  map<ll,ll>::iterator itr = ma.begin();
  while(itr!=ma.end()){
    ll a1 = (*itr).fi;
    ll b1 = (*itr).se;
    ans += (b1-1)*(a+b);
    itr++;
  }
  cout << ans << endl;
	return 0;
}