CSP-JT4 75???

#include<bits/stdc++.h>
#define int long long
using namespace std;
struct Node{
	int x,y;
}pp;
vector<Node>a[10010];
int n,m,k,i,x,y,z,ii,j,mi;
signed main(){
	freopen("bus.in","r",stdin);
	freopen("bus.out","w",stdout);
	ios::sync_with_stdio(0);
	cin.tie(0);cout.tie(0);
	cin>>n>>m>>k;
	for(i=1;i<=m;i++){
		cin>>x>>y>>z;
		pp.x=y,pp.y=z;
		a[x].push_back(pp);
	}
	queue<int>q,p;
	mi=2e9;
	for(ii=0;ii<mi;ii+=k){
		while(!q.empty())q.pop(),p.pop();
		q.push(1);
		p.push(ii);
		while(!q.empty()){
			x=q.front();
			y=p.front();
			if(x==n&&y%k==0){
				mi=min(mi,y);
				break;
			}
			for(i=0;i<a[x].size();i++)
			  if(a[x][i].y<=y+1){
			  	q.push(a[x][i].x);
			  	p.push(y+1);
			  }
			q.pop();
			p.pop();
		}
	}
	if(mi==2e9)cout<<-1;
	else cout<<mi;
	return 0;
}