#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define f(i,a,b) for(ll i=a;i<=b;i++)
#define wt int tt=d;while(tt--)
#define py puts("Yes")
#define pn puts("No")
#define fe(i,e) for(int i=0;i<e.size();i++)
#define vi vector<ll>
inline ll rd() {
	ll x=0,f=1;
	char c=getchar();
	while(!isdigit(c)){if(c=='-')f=-1;c=getchar();}
	while(isdigit(c))x=x*10+c-'0',c=getchar();
	return x*f;
}
#define d rd()
#define pb push_back
ll n,m;
struct edge{ll v,w,nx;}e[400010];
ll hd[200010],cnt;
void add(ll u,ll v,ll w){e[++cnt]=(edge){v,w,hd[u]};hd[u]=cnt;}
map<array<int,2>,bool>vis;
map<array<int,2>,ll>dis;
map<array<int,3>,bool>forb;
priority_queue<array<ll,3>,vector<array<ll,3>>,greater<array<ll,3>>>q;
ll res=0x3f3f3f3f3f3f3f3f;
int main(){
	n=d,m=d;
    f(i,1,m){
        ll u=d,v=d,w=d;
        add(u,v,w);
    }
    ll __=d;
    f(i,1,__){
        int a=d,b=d,c=d;
        forb[{a,b,c}]=1;
    }dis[{0,1}]=0;q.push({0,0,1});
    while(!q.empty()){
        auto qwq=q.top();q.pop();
        ll ds=qwq[0];int pre=qwq[1],u=qwq[2];
        if(vis[{pre,u}])continue;vis[{pre,u}]=1;
        // cout<<pre<<" "<<u<<" "<<ds<<endl;
        if(u==n)res=min(res,ds);
        for(int i=hd[u];i;i=e[i].nx){
            int v=e[i].v;ll w=e[i].w;
            if(pre<u&&u<v&&forb[{pre,u,v}])continue;
            if(dis.find({u,v})==dis.end()||dis[{u,v}]>ds+w){
                dis[{u,v}]=ds+w;
                // cout<<pre<<" "<<u<<" "<<v<<" "<<ds<<" "<<w<<endl;
                q.push({dis[{u,v}],u,v});
            }
        }
    }if(res==0x3f3f3f3f3f3f3f3f)puts("-1");
    else cout<<res;
	return 0;
}