#include <cstdio>
#include <iostream>

using namespace std;

#define MAX 1003


int main()
{
    int mat[MAX][MAX], east[MAX][MAX], south[MAX][MAX], west[MAX][MAX], north[MAX][MAX];
    int n, k, i, j, count = 0;
    cin >> n >> k;

    for(i=0; i<n; i++)
        for(j=0; j<n; j++)
            mat[i][j] = east[i][j] = south[i][j] = west[i][j] = north[i][j] = 0;

    for(i=0; i<k; i++){
        cin >> i >> j;
        mat[i][j] = 1;
    }

    //west
    for(i=0; i<n; i++){
        for(j=1; j<n; j++){
            west[i][j] = west[i][j-1] + mat[i][j-1];

    //north
    for(i=1; i<n; i++){
        for(j=0; j<n; j++){
            north[i][j] = north[i-1][j] + mat[i-1][j];

    //south
    for(i=n-2; i>=0; i--){
        for(j=0; j<n; j++){
            south[i][j] = south[i+1][j] + mat[i+1][j];

    //east
    for(i=0; i<n; i++){
        for(j=n-2; j>=0; j--)
            east[i][j] = east[i][j+1] + mat[i][j+1];

    for(i=0; i<n; i++){
        for(j=0; j<n; j++){
            if(mat[i][j] != 0 && west[i][j] > 0 && south[i][j] > 0 && north[i][j] > 0 && east[i][j] > 0)
                count++;
        }
    }
    cout << count << endl;
    return 0;

}