import java.io.*;
import java.util.Arrays;

class Main{

static final PrintWriter out=new PrintWriter(System.out);
static final int INF=Integer.MAX_VALUE/2;

public static void main(String[] args) throws IOException{
BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
String line=br.readLine();
int n=Integer.parseInt(line.split(" ")[0]);
int m=Integer.parseInt(line.split(" ")[1]);
int[][] score=new int[n][n];
int[][] dp=new int[n*n+1][n*(n-1)/2+1];
Arrays.fill(dp[n*n],INF);
dp[n*n][0]=0;
while(m-->0){
line=br.readLine();
int a=Integer.parseInt(line.split(" ")[0]);
int b=Integer.parseInt(line.split(" ")[1]);
score[a][b]=Integer.parseInt(line.split(" ")[2]);
}
for(int i=n*n-1;i>=0;i--){
for(int j=0;j<=n*(n-1)/2;j++){
if(j==0||(int)i/n==i%n) dp[i][j]=dp[i+1][j];
else dp[i][j]=Math.max(dp[i+1][j],dp[i+1][j-1]+score[(int)i/n][i%n]);
}
}
out.println(dp[0][n*(n-1)/2]);
}
}