#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
inline ll read(){
	ll x=0,f=1;
	char c=getchar();
	while(c<'0'||c>'9'){
		if(c=='-') f=-1;
		c=getchar();
	}
	while(c>='0'&&c<='9'){
		x=(x<<3)+(x<<1)+c-'0';
		c=getchar();
	}
	return x*f;
}
inline void write(ll x){
	if(x<0){
		x=-x;
		putchar('-');
	}
	if(x>9) write(x/10);
	putchar(x%10+'0');
}
const int N=1e6+1e3+5;
int n,p,k,d[N],vis[N],ans=0x7fffffff;
struct node{
	int i,v;
	friend bool operator <(const node a,const node b){
		return a.v>b.v;
	}
};
vector<node> v[N];
void spfa(){
	priority_queue<node> q;
	d[1]=0;
	q.push({1,0});
	vis[1]=1;
	while(!q.empty()){
		int u=q.top().i;
		q.pop();
		for(auto i:v[u]){
			d[i.i]=min(d[i.i],max(d[u],i.v));
			if(!vis[i.i]){
				vis[i.i]=1;
				q.push({i.i,d[i.i]});
			}
		}
	}
	for(int i=n;i<=n*k+n;i+=n){
		ans=min(ans,d[i]);
	}
}
int main(){
	memset(d,0x3f,sizeof d);
	n=read(),p=read(),k=read();
	for(int i=1;i<=p;i++){
		int a=read(),b=read(),l=read();
		for(int j=0;j<k;j++){
			v[a+j*n].push_back({b+j*n,l});
			v[b+j*n].push_back({a+j*n,l});
			v[a+j*n].push_back({b+j*n+n,0});
			v[b+j*n].push_back({a+j*n+n,0});
		}
	}
	spfa();
	if(ans==0x3f3f3f3f){
		write(-1);
		return 0;
	}
	write(ans);
	return 0;
}