#include<bits/stdc++.h>
using namespace std;
#define pii pair<int,int>
#define fi first
#define se second
int k,ti[10005][105];
vector<pii> g[10005];
bool vis[10005][105];
void dij(){
	priority_queue<pii,vector<pii>,greater<pii> > q;
	memset(ti,0x3f,sizeof ti);
	q.push({ti[1][0]=0,1});
	while(!q.empty()){
		int u=q.top().second,tmp=q.top().first; q.pop();
		if(vis[u][tmp%k])continue;
		vis[u][tmp%k]=true;
		for(auto i:g[u]){
			//AC
			int moo=tmp;
			while(moo<i.se)moo+=k;
			if(ti[i.fi][(moo+1)%k]>moo+1)ti[i.fi][(moo+1)%k]=moo+1,q.push({moo+1,i.fi});
			//WA 85pts
//			while(tmp<i.se)tmp+=k;
//			if(ti[i.fi][(tmp+1)%k]>tmp+1)ti[i.fi][(tmp+1)%k]=tmp+1,q.push({tmp+1,i.fi});
		}				
	} 	
}
int main(){
	int n,m,u,v,a;
	cin>>n>>m>>k;
	while(m--)cin>>u>>v>>a,g[u].push_back({v,a});
	dij(),cout<<(vis[n][0]?ti[n][0]:-1);
	return 0;
}

rt，请问AC和WA的写法在本题中到底有什么区别？