// <zaw.cpp> - Thu Oct  6 08:17:54 2016
// This file is made by YJinpeng，created by XuYike's black technology automatically.
// Copyright (C) 2016 ChangJun High School, Inc.
// I don't know what this program is.

#include <iostream>
#include <vector>
#include <algorithm>
#include <cstring>
#include <cstdio>
#include <cstdlib>
#include <cmath>
#include <queue>
#define INF 1e9
#define IN inline
#define RG register
using namespace std;
typedef long long LL;
inline int gi() {register int w=0,q=0;register char ch=getchar();while((ch<'0'||ch>'9')&&ch!='-')ch=getchar();if(ch=='-')q=1,ch=getchar();while(ch>='0'&&ch<='9')w=w*10+ch-'0',ch=getchar();return q?-w:w;
}
const int N=5010,M=N<<2;
int n,m,t,ans;int d[N],fr[N];int to[M],ne[M],W[M];bool u[N];
struct node{int s,p;bool operator<(node a)const{return s>a.s;}
};
priority_queue<node>q;
IN void link(RG int u,RG int v,RG int w){to[++t]=v;ne[t]=fr[u];fr[u]=t;W[t]=w;//if(u==1)cout<<v<<endl;this
}
void read(){n=gi(),m=gi();while(m--){int u=gi(),v=gi(),w=gi(),w1=gi();link(u,v,w);link(v,u,w1);}
}
IN int Dij(RG int begin,RG int end,int w){for(int i=1;i<=n;i++)d[i]=INF;q.push((node){d[begin]=0,begin});memset(u,0,sizeof(u));while(!q.empty()){while(u[q.top().p]&&!q.empty())q.pop();if(q.empty())break;int x=q.top().p;q.pop();u[x]=1;if(w+d[x]>=ans)break;//thisif(x==end)return d[1];for(int o=fr[x],y;y=to[o],o;o=ne[o])if(d[x]+W[o]<d[y]){d[y]=d[x]+W[o];if(d[y]>=ans)continue;//this
                q.push((node){d[y],y});}}return d[1];
}
void Work(){read();ans=INF;for(int i=fr[1],w;i;i=ne[i]){if(W[i]>=ans)continue;//thisif(i&1)w=W[i+1],W[i+1]=INF;else w=W[i-1],W[i-1]=INF;ans=min(ans,W[i]+Dij(to[i],1,W[i]));if(i&1)W[i+1]=w;else W[i-1]=w;}printf("%d",ans);
}
int main()
{freopen("zaw.in","r",stdin);freopen("zaw.out","w",stdout);Work();return 0;
}

#include<iostream>
#include<cstdlib>
#include<cstdio>
#include<cmath>
#include<algorithm>
#include<vector>
#include<queue>
#define in long long
using namespace std;
in getint(){in res=0,f=1;char c=getchar();while(c!='-' &&(c<'0' || c>'9'))c=getchar();if(c=='-'){f=-1;c=getchar();}while(c>='0' && c<='9'){res=res*10+c-'0';c=getchar();}return res*f;
}
struct lnode{int data,v,rev;bool g;lnode *next;
}*a[100001];
int n,m,k,top=1,tail=1,ans=999999999;
int d[100001][2],col[100001]={0},c[100001]={0};
int q[100001];
bool instack[100001]={0};
void spfa(int i){int x=q[i];lnode *p=a[x];while(p){if(d[p->data][0]>d[x][0]+p->v){if(instack[p->data]==false){instack[p->data]=true;d[p->data][0]=d[x][0]+p->v;col[p->data]=col[x];q[top++]=p->data;if(top>100000)top=1;}else{d[p->data][0]=d[x][0]+p->v;col[p->data]=col[x];}}p=p->next;}
}
void spfb(int i) {int x=q[i]; lnode *p=a[x]; while(p) { if(d[p->data][1]>d[x][1]+p->rev) { if(instack[p->data]==false) { instack[p->data]=true; d[p->data][1]=d[x][1]+p->rev; c[p->data]=c[x]; q[top++]=p->data;if(top>100000)top=1; }else { d[p->data][1]=d[x][1]+p->rev; c[p->data]=c[x]; } if(c[p->data]!=col[p->data])ans=min(ans,d[p->data][0]+d[p->data][1]); } else if(col[p->data]!=0 && c[x]!=col[p->data]) ans=min(ans,d[p->data][0]+d[x][1]+p->rev); p=p->next; }
}
int main()
{freopen("zaw.in","r",stdin);freopen("zaw.out","w",stdout);n=getint();m=getint();for(int i=1;i<=n;++i)a[i]=NULL,d[i][0]=999999999,d[i][1]=999999999;for(int i=1;i<=m;++i){int x=getint(),y=getint(),z1=getint(),z2=getint();;lnode *p=new lnode;p->data=y;p->v=z1;p->rev=z2;p->next=a[x];a[x]=p;p=new lnode;p->data=x;p->v=z2;p->rev=z1;p->next=a[y];a[y]=p;}lnode *p=a[1];int now=0;instack[1]=true;d[1][0]=0;while(p){q[top++]=p->data;col[p->data]=++now;d[p->data][0]=p->v;instack[p->data]=true;p=p->next;}while(tail!=top){spfa(tail);instack[q[tail]]=false;tail++;if(tail>100000)tail=1;}for(int i=2;i<=n;++i)instack[i]=false;instack[1]=true;d[1][1]=0;p=a[1];top=1;tail=1;now=0;while(p){q[top++]=p->data;c[p->data]=++now;d[p->data][1]=p->rev;instack[p->data]=true;p=p->next;}while(tail!=top){spfb(tail);instack[q[tail]]=false;tail++;if(tail>100000)tail=1;}cout<<ans;return 0;
}