volcanoe

process.stdin.resume();
process.stdin.setEncoding('ascii');

var input_stdin = "";
var input_stdin_array = "";
var input_currentline = 0;

process.stdin.on('data', function (data) {
    input_stdin += data;
});

process.stdin.on('end', function () {
    input_stdin_array = input_stdin.split("\n");
    main();    
});

function readLine() {
    return input_stdin_array[input_currentline++];
}

/////////////// ignore above this line ////////////////////

function main() {
    var history = [];
    var grid = [];
    
    var n = parseInt(readLine()); 
    for(var i = 0; i < n; i++){
        grid.push([]);
        for(var j = 0; j < n; j++){
            grid[i].push(0);
        }
    }
        
    var m = parseInt(readLine());
    for(var a0 = 0; a0 < m; a0++){
        var x_temp = readLine().split(' ');
        var x = parseInt(x_temp[0]);
        var y = parseInt(x_temp[1]);
        var w = parseInt(x_temp[2]);
        // Write Your Code Here
        var r = 1;
        var yw = 0;
        for(; w >= 0; w--){
                //r = 3
                var radiusX = Math.floor(r/2);
                var radiusY = r - 2;
                for(let xr = x - radiusX; xr < x + radiusX; xr++){
                    if(indexIsInBounds(y + radiusX, xr, grid)){
                           grid[y+radiusX][xr] += w;
                    }
                    if(radiusX != 0){
                        if(indexIsInBounds(y - radiusX, xr, grid)){
                            grid[y-radiusX][xr] += w;
                        }
                    }
                }
            
                for(let yr = y - yw; yr < y - yw + radiusY + 2; yr++){
                     if(indexIsInBounds(yr, x + yw, grid)){
                         grid[yr][x + yw] += w;
                     }
                    
                     
                }
                for(let yr = y - yw + 1; yr < y - yw + radiusY + 1; yr++){
                     if(indexIsInBounds(yr, x - yw, grid)){
                         grid[yr][x - yw] += w;
                     }
                }
            
            r+=2;
            yw++;

        }
    }
    
    var max = 0;
    for(var i = 0; i < n; i++){
        for(var j = 0; j < n; j++){
            if(grid[i][j] > max){
                max = grid[i][j];
            }
        }
    }
    console.log(max);
}
                
function indexIsInBounds(x,y, grid){
    if(x < 0 || y < 0){
        return false;
    }
    if(grid.length > x && grid[x].length > y){
        return true;
    }else{
        return false;
    }
}