#include<bits/stdc++.h>
using namespace std;
struct node {
int x, y, z;
}a[30];
int main() {
int d, n;
cin >> d >> n;
for (int i = 1; i <= n; i++)
cin >> a[i].x >> a[i].y >> a[i].z;
int ans = 0;
for (int i = 0; i <= 1024; i++) {
for (int j = 0; j <= 1024; j++) {
int sum = 0;
for (int k = 1; k <= n; k++) {
if (abs(a[k].x - i) <= d && abs(a[k].y - j) <= d) {
sum += a[k].z;
}
}
if (ans < sum) ans = sum;
}
}
cout << ans;
return 0;
}
