#include <iostream>
#include <cmath>
#include <algorithm>
#define int long long
using namespace std;

const int N = 1010;
int n, k;

struct node{
    int x, y;
    bool operator < (const node &p)const{
        if(x != p.x)return x < p.x;
        else return y < p.y;
    }

}a[N];

int dp[N];

int oj(node a, node b){
    return sqrt((a.x-b.x)*(a.x-b.x)+(a.y-b.y)*(a.y-b.y));
}

int mhd(node a, node b){
    return abs(a.x-b.x) + abs(a.y-b.y);
}

int ans = 1;

signed main(){
    cin >> n >> k;
    for(int i = 1; i <= n; i++){
        cin >> a[i].x >> a[i].y;
        dp[i] = 1;
    }
    sort(a+1, a+1+n);
    for(int i = 1; i <= n; i++){
        for(int j = 1; j < i; j++){
            if(a[i].y >= a[j].y && mhd(a[i], a[j]) == 1){
                dp[i] = max(dp[i], dp[j]+1);
            }
        }
    }

    for(int i = 1; i <= n; i++){
        ans = max(ans, dp[i]);
    }

    cout << ans+k;

    return 0;
}