#include<iostream>
#include<cstdio>
#include<cstring>
using namespace std;
int a[210][210],n;
void init()
{
	int m,x,y,k;
	cin>>n>>m;
	for(int i=0;i<m;i++)
	{
		cin>>x>>y>>k;
		a[x][y]=k;
	}
}
int main()
{
	freopen("hardest.in","r",stdin);
	freopen("hardest.out","w",stdout);
	int N;
	cin>>N;
	memset(a,0,sizeof(a));
	while(N)
	{
		n=0;
		init();
		for(int k=1;k<=n;k++)
			for(int i=1;i<=n;i++)
				for(int j=1;j<=n;j++)
				{
					if((a[i][k]+a[k][j]<a[i][j]&&a[i][k]!=0&&a[k][j]!=0)||a[i][j]==0)
					{  
						a[i][j]=a[i][k]+a[k][j];  
					}
				}
if(a[1][n]){
		cout<<a[1][n]<<endl;}
else{
cout<<-1<<endl;}
		memset(a,0,sizeof(a));
		N--;
	}
	return 0;
}