#include<iostream>
#include<cstring>
#include<algorithm>
using namespace std;
const int N=510,M=10010;//点,边
int n,m,k;
int dist[N],backup[N];//backup上次迭代的结果
struct Edge
{
int a,b,w;//起点终点边权
}edges[M];
int bellman_ford()
{
memset(dist,0x3f,sizeof dist);
dist[1]=0;
cout<<"111";
for(int i=0;i<k;i++)
{
memcpy(backup,dist,sizeof dist);
for(int j=0;i<m;j++)
{
int a=edges[j].a;
int b=edges[j].b;
int w=edges[j].w;
dist[b]=min(dist[b],backup[a]+w);
}
}
if(dist[n]>(0x3f3f3f3f/2))return -1;
return dist[n];
}
int main()
{
cin>>n>>m>>k;
for(int i=0;i<m;i++)
{
int a,b,w;
cin>>a>>b>>w;
edges[i]={a,b,w};
}
int t;
t=bellman_ford();
cout<<"222"<<endl;
if(t==-1)puts("impossible");
else
cout<<t<<endl;
return 0;
}
找不到错在哪啊