#include <iostream>
#include <cstdio>
#include <vector>
#include <queue>
#include <utility>
using namespace std;

int N, M, T;
vector < pair<int, int> > apples;
int delta[4][2] = { {-1, 0}, {0, 1}, {1, 0}, {0, -1} };

void input()
{
    scanf("%d %d %d", &N, &M, &T);
    int x, y;
    scanf("%d %d", &x, &y);
    apples.push_back(make_pair(x-1, y-1));
    if( scanf("%d %d", &x, &y) == 2 )
        apples.push_back(make_pair(x-1, y-1));
}

bool used[1000][1000];
void bfs()
{
    queue < pair<int, int> > q;
    int x, y;
    for( int i = 0; i < apples.size(); i++ )
    {
        x = apples[i].first;
        y = apples[i].second;
        q.push(make_pair(x, y));
        used[x][y] = 1;
    }
    int br1 = q.size(), levels = 0;
    int rotten_apples = q.size();

    while( !q.empty() )
    {
        int x = q.front().first;
        int y = q.front().second;
        q.pop();
        br1--;

        for( int i = 0; i < 4; i++ )
        {
            int new_x = x + delta[i][0];
            int new_y = y + delta[i][1];
            if( 0 <= new_x && new_x < N && 0 <= new_y && new_y < M && !used[new_x][new_y] )
            {
                used[new_x][new_y] = 1;
                q.push(make_pair(new_x, new_y));
            }
        }

        if( br1 == 0 )
        {
            br1 = q.size();
            rotten_apples += q.size();
            levels++;
        }
        if( levels == T )
        {
            printf("%d\n", N*M - rotten_apples);
            break;
        }
    }
}

int main()
{
    input();
    bfs();

    return 0;
}