#include <cstdio>#include <cstring>#include <iostream>#include <stack>using namespace std;const int INF=0x3fffffff;const int N=50006;const int E=160006;struct Edge{ int st, en, val, next; Edge() {} Edge(int a, int b, int c, int d) { st=a, en=b, val=c, next=d; }} edge[E];int head[N], tot;int cnt[N], dis[N];bool vs[N];stack<int> S;void add_edge(int st, int en, int val){ edge[tot]=Edge(st, en, val, head[st]); head[st]=tot++;}int SPFA(int s, int t, int n){ for(int i=0; i<=n; i++) vs[i]=false, dis[i]=-INF, cnt[i]=0; while(!S.empty()) S.pop(); S.push(s), vs[s]=true, dis[s]=0, cnt[s]++; while(!S.empty()) { int u=S.top(); S.pop(), vs[u]=false; if(cnt[u]>n) return -1; for(int e=head[u]; e!=-1; e=edge[e].next) { int v=edge[e].en; int val=edge[e].val; if(dis[v]<dis[u]+val) { dis[v]=dis[u]+val; if(!vs[v]) vs[v]=true, S.push(v), cnt[v]++; } } } return dis[t];}int main(){ int n; while(scanf("%d", &n)!=EOF) { memset(head, -1, sizeof head); tot=0; int Max=0; for(int i=0, a, b, c; i<n; i++) { scanf("%d%d%d", &a, &b, &c); Max=max(Max, b); add_edge(a, b+1, c); } for(int i=1; i<=Max+1; i++) add_edge(i, i-1, -1), add_edge(i-1, i, 0); int ans=SPFA(1, Max+1, Max+1); printf("%dn", ans); } return 0;}
