Apples2

// ConsoleApplication1.cpp : Defines the entry point for the console application.
//

#include "stdafx.h"
#include <iostream>
#include <vector>
#include <set>

using namespace std;

set<pair<int, int> > pestilence(set < pair<int, int> > apples, int x, int y, int rows, int cols) {

    set<pair<int, int> > tempCoord;


    if (y > 0)
        tempCoord.insert(make_pair(x, y - 1));

    if ( x > 0)
        tempCoord.insert(make_pair(x - 1, y));

    if (x+1 <= rows)
        tempCoord.insert(make_pair(x + 1, y));

    if (y+1 <= cols)
        tempCoord.insert(make_pair(x, y + 1));


        return tempCoord;
}

struct Contained {

};

int main()
{
    int rows, cols, days;
    set<pair <int, int> > badApple;
    set<pair <int, int> > badApplesNew;

    cin >> rows >> cols >> days;

    int bads;
    cin >> bads;

    for (int i = 0; i < bads; i++) {
        int x, y;
        cin >> x >> y;
        badApple.insert(make_pair(x, y));

    }



    for (int i = 1; i <= days; i++) {
        set<pair<int, int> >::iterator it = badApple.begin();
        for (it = badApple.begin(); it != badApple.end(); it++) {
            auto tempSet = pestilence(badApple, it->first, it->second, rows, cols);
            badApplesNew.insert(tempSet.begin(), tempSet.end());
        }
        badApple.insert(badApplesNew.begin(), badApplesNew.end());
    }

    cout << badApple.size() << endl;

    return 0;
}