#include<iostream>
#include<fstream>
#include<bitset>
#include<vector>
#include<deque>
#include<map>
#include<set>
#include<queue>
#include<string>
#include<algorithm>
#include<cmath>
#include<ctime>
#include<cstdio>
using namespace std;
#if defined wolf
const string ok="OK";
const string kk="	";
ofstream nnew("KZstartravelillu.in",ios::app);
ifstream fin("KZstartravelillu.in");
#define fout cout
#define Endl endl
#else
ifstream fin("KZstartravelillu.in");
ofstream fout("KZstartravelillu.out");
#endif
class node{
public:
	int from,to;
	int len;
	node(){
	}
	node(int a,int b,int c){
		from=a;
		to=b;
		len=c;
	}
};
vector<vector<int> > index;
vector<node> TT;
int core(int n){
	queue<int> Q;
	Q.push(1);
	vector<bool> flag;
	vector<int> dis;
	dis.resize(index.size(),999999999);
	flag.resize(index.size(),0);
	dis[1]=0;
	while(!Q.empty()){
		int it=Q.front();
		Q.pop();
		flag[it]=0;
		for(int i=0;i!=index[it].size();++i){
			node& pp=TT[index[it][i]];
			if(dis[pp.to]>dis[pp.from]+pp.len){
				dis[pp.to]=dis[pp.from]+pp.len;
				if(flag[pp.to]){
					continue;
				}
				flag[pp.to]=1;
				Q.push(pp.to);
			}
		}
	}
	return dis[n];
}
int main(){
	int n,m;
	fin>>n>>m;
	index.resize(n+5);
	for(int i=0;i!=m;++i){
		int a,b,c;
		fin>>a>>b>>c;
		index[a].push_back(TT.size());
		TT.push_back(node(a,b,c));
		index[b].push_back(TT.size());
		TT.push_back(node(b,a,c));
	}
	fout<<core(n)<<endl;
	//-------------------------*/
	#if defined wolf
	cout<<endl<<(double)clock()/CLOCKS_PER_SEC<<'s'<<endl;
	#endif
	return 0;
}
//Designed by wolf
//Fri Apr 24 2015