#include <stdio.h>
#include <vector>
#include <map>
#include <queue>

std::vector<int> V[100010];
std::map< std::pair<int,int> , int > M,M2;
std::priority_queue< std::pair<long long int,int> , std::vector< std::pair<long long int,int> > , std::greater< std::pair<long long int, int > > > Q;
long long int dist[100010];
int prev[100010];
long long int MAX = 1;
int a;

long long int func(int start, int end)
{
	for(int i=1;i<=a;i++) dist[i] = MAX;
	Q.push(std::make_pair(0,start));
	dist[start] = 0;
	
	while(!Q.empty())
	{
		long long int S = Q.top().first;
		int t = Q.top().second;
		Q.pop();
		if(dist[t]!=S) continue;
		
		for(int i=0;i<V[t].size();i++)
		{
			if(dist[V[t][i]]>S+M[std::make_pair(t,V[t][i])])
			{
				dist[V[t][i]] = S+M[std::make_pair(t,V[t][i])];
				prev[V[t][i]] = t;
				Q.push(std::make_pair(S+M[std::make_pair(t,V[t][i])],V[t][i]));
			}
		}
	}
	
	int p = end;
	while(p!=start)
	{
		M[std::make_pair(p,prev[p])] = M2[std::make_pair(p,prev[p])];
		M[std::make_pair(prev[p],p)] = M2[std::make_pair(p,prev[p])];
		p = prev[p];
		if(p==0) break;
	}
	return dist[end];
}
int main()
{
	for(int i=1;i<=15;i++) MAX*=10;
	
	int b;
	scanf("%d%d",&a,&b);
	for(int i=1;i<=b;i++)
	{
		int c,d,e,f;
		scanf("%d%d%d%d",&c,&d,&e,&f);
		V[c].push_back(d);
		V[d].push_back(c);
		M[std::make_pair(c,d)] = e;
		M[std::make_pair(d,c)] = e;
		M2[std::make_pair(c,d)] = f;
		M2[std::make_pair(d,c)] = f;
	}
	
	long long int S1 = func(1,a);
	long long int S2 = func(a,1);
	printf("%lld",S1+S2);
}