#include <map>
#include <set>
#include <ctime>
#include <cmath>
#include <queue>
#include <stack>
#include <vector>
#include <string>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <sstream>
#include <iostream>
#include <algorithm>
#include <functional>
using namespace std;
#define For(i, x, y) for(int i=x;i<=y;i++)
#define _For(i, x, y) for(int i=x;i>=y;i--)
#define Mem(f, x) memset(f,x,sizeof(f))
#define Sca(x) scanf("%d", &x)
#define Sca2(x,y) scanf("%d%d",&x,&y)
#define Scl(x) scanf("%lld",&x);
#define Pri(x) printf("%d\n", x)
#define Prl(x) printf("%lld\n",x);
#define CLR(u) for(int i=0;i<=N;i++)u[i].clear();
#define LL long long
#define ULL unsigned long long
#define mp make_pair
#define PII pair<int,int>
#define PIL pair<int,long long>
#define PLL pair<long long,long long>
#define pb push_back
#define fi first
#define se second
typedef vector<int> VI;
const double eps = 1e-9;
const int maxn = 110;
const int maxm = 20010;
const int INF = 0x3f3f3f3f;
const int mod = 1e9 + 7;
int N,M,tmp,K;
inline int read()
{int now=0;register char c=getchar();for(;!isdigit(c);c=getchar());for(;isdigit(c);now=now*10+c-'0',c=getchar());return now;
}
struct Node{int L,P,S;
}node[maxn];
int dp[2][maxm];
bool cmp(Node a,Node b){return a.S < b.S;
}
int DP[maxm][20];
int mm[maxm];
int num[maxm];
void initRMQ(int n,int b[]){mm[0] = -1;for(int i = 1; i <= n ; i ++){mm[i] = ((i & (i - 1)) == 0) ? mm[i - 1] + 1:mm[i - 1];DP[i][0] = b[i];}for(int j = 1; j <= mm[n]; j ++){for(int i = 1; i + (1 << j) - 1 <= n ; i++){DP[i][j] = max(DP[i][j - 1],DP[i + (1 << (j - 1))][j - 1]);}}
}
int rmq(int x,int y){int k = mm[y - x + 1];return max(DP[x][k],DP[y - (1 << k) + 1][k]);
}
int main()
{while(~Sca2(N,K)){For(i,1,K){scanf("%d%d%d",&node[i].L,&node[i].P,&node[i].S);}sort(node + 1,node + 1 + K,cmp);Mem(dp,0);For(i,1,K){Mem(num,0);Mem(dp[i & 1],0);for(int k = max(node[i].S - node[i].L + 1,1); k <= node[i].S; k ++){num[k] = dp[i - 1 & 1][k - 1] - node[i].P * (k - 1);}initRMQ(node[i].S,num);For(j,1,N){dp[i & 1][j] = max(dp[i - 1 & 1][j],dp[i & 1][j - 1]);if(j >= node[i].S && j <= node[i].S + node[i].L - 1){dp[i & 1][j] = max(dp[i & 1][j],rmq(max(j - node[i].L + 1,1),node[i].S) + node[i].P * j);}} }Pri(dp[K & 1][N]);}#ifdef VSCodesystem("pause");#endifreturn 0;
}

#include <map>
#include <set>
#include <ctime>
#include <cmath>
#include <queue>
#include <stack>
#include <vector>
#include <string>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <sstream>
#include <iostream>
#include <algorithm>
#include <functional>
using namespace std;
#define For(i, x, y) for(int i=x;i<=y;i++)
#define _For(i, x, y) for(int i=x;i>=y;i--)
#define Mem(f, x) memset(f,x,sizeof(f))
#define Sca(x) scanf("%d", &x)
#define Sca2(x,y) scanf("%d%d",&x,&y)
#define Scl(x) scanf("%lld",&x);
#define Pri(x) printf("%d\n", x)
#define Prl(x) printf("%lld\n",x);
#define CLR(u) for(int i=0;i<=N;i++)u[i].clear();
#define LL long long
#define ULL unsigned long long
#define mp make_pair
#define PII pair<int,int>
#define PIL pair<int,long long>
#define PLL pair<long long,long long>
#define pb push_back
#define fi first
#define se second
typedef vector<int> VI;
const double eps = 1e-9;
const int maxn = 110;
const int maxm = 20010;
const int INF = 0x3f3f3f3f;
const int mod = 1e9 + 7;
int N,M,tmp,K;
inline int read()
{int now=0;register char c=getchar();for(;!isdigit(c);c=getchar());for(;isdigit(c);now=now*10+c-'0',c=getchar());return now;
}
struct Node{int L,P,S;
}node[maxn];
int dp[2][maxm];
bool cmp(Node a,Node b){return a.S < b.S;
}
int Queue[maxm];
int head,tail;
int main()
{while(~Sca2(N,K)){For(i,1,K){scanf("%d%d%d",&node[i].L,&node[i].P,&node[i].S);}sort(node + 1,node + 1 + K,cmp);Mem(dp,0);For(i,1,K){head = 1; tail = 0;Mem(dp[i & 1],0);for(int k = max(node[i].S - node[i].L + 1,1); k <= node[i].S; k ++){int ans = dp[i - 1 & 1][k - 1] - node[i].P * (k - 1);while(head <= tail && dp[i - 1 & 1][Queue[tail] - 1] - node[i].P * (Queue[tail] - 1)<= ans) tail--;Queue[++tail] = k;}For(j,1,N){dp[i & 1][j] = max(dp[i - 1 & 1][j],dp[i & 1][j - 1]);if(j >= node[i].S){while(head <= tail && Queue[head] < j - node[i].L + 1) head++;if(head <= tail) dp[i & 1][j] = max(dp[i & 1][j],dp[i - 1 & 1][Queue[head] - 1] + (j - Queue[head] + 1) * node[i].P);}} }Pri(dp[K & 1][N]);}#ifdef VSCodesystem("pause");#endifreturn 0;
}