While exploring his many farms, Farmer John has discovered a number of amazing wormholes. A wormhole is very peculiar because it is a one-way path that delivers you to its destination at a time that is BEFORE you entered the wormhole! Each of FJ's farms comprises N (1 ≤ N ≤ 500) fields conveniently numbered 1..N, M (1 ≤ M ≤ 2500) paths, and W (1 ≤ W ≤ 200) wormholes.

As FJ is an avid time-traveling fan, he wants to do the following: start at some field, travel through some paths and wormholes, and return to the starting field a time before his initial departure. Perhaps he will be able to meet himself :) .

To help FJ find out whether this is possible or not, he will supply you with complete maps to F (1 ≤ F ≤ 5) of his farms. No paths will take longer than 10,000 seconds to travel and no wormhole can bring FJ back in time by more than 10,000 seconds.

#include
     
       #include
      
        #include
       
         #include
        
          #include
         
           #include
          
            using namespace std; #define inf 0x3f3f3f3f struct Edge{ int f,t,c; }edge[6000]; int dist[505]; int cas,n,m,h,cnt; int bellman() { fill(dist,dist+503+1,inf); dist[1]=0;int j; for(j=1;j<=n;j++) { bool flag=false; for(int i=1;i<=cnt;i++) { int from=edge[i].f,to=edge[i].t,cost=edge[i].c; if(dist[to]>dist[from]+cost) { flag=true; dist[to]=dist[from]+cost; } } if(!flag) break; } if(j==n+1) return 1; else return 0; } int main() { scanf("%d",&cas); while(cas--) { cnt=0; scanf("%d %d %d",&n,&m,&h); int u,v,w; for(int i=1;i<=m;i++) { cnt++; scanf("%d %d %d",&u,&v,&w); edge[cnt].f=u; edge[cnt].t=v; edge[cnt].c=w; cnt++; edge[cnt].f=v; edge[cnt].t=u; edge[cnt].c=w; } for(int i=1;i<=h;i++) { cnt++; scanf("%d %d %d",&u,&v,&w); edge[cnt].f=u; edge[cnt].t=v; edge[cnt].c=-w; } if(bellman()) printf("YES\n"); else printf("NO\n"); } return 0; }