C++ :

#include<cstdio>
#include<queue>
#include<cstring>
#define MAXK 10001
#define MAXN 1001
#define INF 10000001
using namespace std;
struct edge{
	int to;
	int data;
	int next;
}e[MAXK<<1];
int n,p,k,len,g[MAXN],dis[MAXN];
bool v[MAXN];
queue<int> q;
void make_edge(int x,int y,int data){
	len++;
	e[len].to=y;
	e[len].data=data;
	e[len].next=g[x];
	g[x]=len;
	return;
}
bool SPFA(int);
int main(){
	scanf("%d%d%d",&n,&p,&k);
	for(int i=1;i<=p;i++){
		int x,y,l;
		scanf("%d%d%d",&x,&y,&l);
		make_edge(x,y,l);
		make_edge(y,x,l);
	}
	int l=0,r=INF,ans=INF;
	while(l<=r){
		int mid=(l+r)>>1;
		bool flag=SPFA(mid);
		if(flag){
			if(ans>mid) ans=mid;
			r=mid-1;
		}
		else l=mid+1;
	}
	if(ans==INF) ans=-1;
	printf("%d\n",ans);
	return 0;
}
bool SPFA(int lim){
	memset(dis,0x7f,sizeof(dis));
	memset(v,0,sizeof(v));
	v[1]=1;
	dis[1]=0;
	q.push(1);
	while(!q.empty()){
		int k=q.front();
		v[k]=0;
		q.pop();
		for(int i=g[k];i!=0;i=e[i].next){
			int y=e[i].to,val=e[i].data;
			int add=0;
			if(val>lim) add=1;
			if(dis[y]>dis[k]+add){
				dis[y]=dis[k]+add;
				if(!v[y]){
					v[y]=1;
					q.push(y);				
				}
			}
		}
	}
	if(dis[n]<=k) return 1;
	return 0;
}