1 #include<cstdio>
2 #include<cstring>
3 #include<algorithm>
4 using namespace std;
5 #define MAXN 50010
6 struct time
7 {
8 int s,t,ef;
9 friend bool operator<(time a,time b)
10 {
11 return a.ef>b.ef;
12 }
13 };
14 struct node
15 {
16 int sum,lazy;
17 };
18 time p[MAXN*10];
19 node tree[MAXN<<2];
20 void Build(int L,int R,int rt)
21 {
22 tree[rt].lazy=0;
23 tree[rt].sum=R-L+1;
24 if(L!=R)
25 {
26 int mid=(L+R)>>1;
27 Build(L,mid,rt<<1);
28 Build(mid+1,R,rt<<1|1);
29 }
30 }
31 inline void PushDown(int rt)
32 {
33 if(tree[rt].lazy)
34 {
35 tree[rt].lazy=0;
36 tree[rt<<1].lazy=tree[rt<<1|1].lazy=1;
37 tree[rt<<1].sum=tree[rt<<1|1].sum=0;
38 }
39 }
40 inline void PushUp(int rt)
41 {
42 tree[rt].sum=tree[rt<<1].sum+tree[rt<<1|1].sum;
43 }
44 int Query(int x,int y,int L,int R,int rt)
45 {
46 if(x<=L&&R<=y)
47 return tree[rt].sum;
48 int ans=0,mid=(L+R)>>1;
49 PushDown(rt);
50 if(x<=mid)
51 ans+=Query(x,y,L,mid,rt<<1);
52 if(y>mid)
53 ans+=Query(x,y,mid+1,R,rt<<1|1);
54 return ans;
55 }
56 void Update(int x,int y,int L,int R,int rt)
57 {
58 if(x<=L&&R<=y)
59 {
60 tree[rt].lazy=1;
61 tree[rt].sum=0;
62 }
63 else
64 {
65 int mid=(L+R)>>1;
66 PushDown(rt);
67 if(x<=mid)
68 Update(x,y,L,mid,rt<<1);
69 if(y>mid)
70 Update(x,y,mid+1,R,rt<<1|1);
71 PushUp(rt);
72 }
73 }
74 int main()
75 {
76 int i,n,m,ans;
77 while(~scanf("%d%d",&n,&m))
78 {
79 Build(0,n-1,1);
80 for(i=0;i<m;i++)
81 scanf("%d%d%d",&p[i].s,&p[i].t,&p[i].ef);
82 sort(p,p+m);
83 for(i=ans=0;i<m;i++)
84 {
85 ans+=p[i].ef*Query(p[i].s,p[i].t-1,0,n-1,1);
86 Update(p[i].s,p[i].t-1,0,n-1,1);
87 }
88 printf("%d\n",ans);
89 }
90 return 0;
91 }
