//12252024832524
#include <bits/stdc++.h>
#define TT template<typename T>
using namespace std; 

typedef long long LL;
const int MAXN = 10005;
const int MAXM = 200005;
const int INF = 0x3f3f3f3f;
int n,m,ans = INF;

LL Read()
{
	LL x = 0,f = 1;char c = getchar();
	while(c > '9' || c < '0'){if(c == '-')f = -1;c = getchar();}
	while(c >= '0' && c <= '9'){x = (x*10) + (c^48);c = getchar();}
	return x * f;
}
TT void Put1(T x)
{
	if(x > 9) Put1(x/10);
	putchar(x%10^48);
}
TT void Put(T x,char c = -1)
{
	if(x < 0) putchar('-'),x = -x;
	Put1(x); if(c >= 0) putchar(c);
}
TT T Max(T x,T y){return x > y ? x : y;}
TT T Min(T x,T y){return x < y ? x : y;}
TT T Abs(T x){return x < 0 ? -x : x;}

int head[MAXN],tot = 1;
struct edge{
	int v,w,nxt;
}e[MAXM<<1];
void Add_Edge(int u,int v,int w){
	e[++tot] = edge{v,w,head[u]};
	head[u] = tot;
}
int dis[2][MAXN];
struct node{
	int x,d;
	bool operator < (const node &px)const{
		return d > px.d;
	}
};
int f[MAXN],g[MAXN];

int main()
{
//	freopen(".in","r",stdin);
//	freopen(".out","w",stdout);
	n = Read(); m = Read();
	for(int i = 1,u,v;i <= m;++ i){
		u = Read(); v = Read();
		Add_Edge(u,v,Read());
		Add_Edge(v,u,Read());
	}
	for(int i = 1;i <= n;++ i) dis[0][i] = INF;
	priority_queue<node> q; q.push(node{1,dis[0][1] = 0});
	while(!q.empty()){
		node t = q.top(); q.pop();
		if(t.d > dis[0][t.x]) continue;
		for(int i = head[t.x],v; i ;i = e[i].nxt)
			if(t.d+e[i].w < dis[0][v = e[i].v]){
				if(t.x == 1) f[v] = i>>1;
				else f[v] = f[t.x];
				q.push(node{v,dis[0][v] = t.d+e[i].w});
			}
	}
	for(int i = 1;i <= n;++ i) dis[1][i] = INF;
	q.push(node{1,dis[1][1] = 0});
	while(!q.empty()){
		node t = q.top(); q.pop();
		if(t.d > dis[1][t.x]) continue;
		for(int i = head[t.x],v; i ;i = e[i].nxt)
			if(t.d+e[i^1].w < dis[1][v = e[i].v]){
				if(t.x == 1) g[v] = i>>1;
				else g[v] = g[t.x];
				q.push(node{v,dis[1][v] = t.d+e[i^1].w});
			}
	}
	for(int x = 1;x <= n;++ x)
		for(int i = head[x],v; i ;i = e[i].nxt)
			if(f[x] != g[v = e[i].v] && f[x] != (i >> 1) && g[v] != (i>>1))
				ans = Min(ans,dis[0][x]+e[i].w+dis[1][v]);
	Put(ans,'\n');
	return 0;
}