//Achen
#include<algorithm>
#include<iostream>
#include<cstring>
#include<cstdlib>
#include<cstdio>
#include<vector>
#include<queue>
#include<ctime>
#include<cmath>
const int N=200000+7;
typedef long long LL;
using namespace std;template<typename T> void read(T &x) {char ch=getchar(); x=0; T f=1;while(ch!='-'&&(ch<'0'||ch>'9')) ch=getchar();if(ch=='-') f=-1,ch=getchar();for(;ch>='0'&&ch<='9';ch=getchar()) x=x*10+ch-'0'; x*=f;
}int n,m,ecnt;
struct edge{int x,y,a,b;edge(){}edge(int x,int y,int a,int b):x(x),y(y),a(a),b(b){} friend bool operator <(const edge&A,const edge&B) {return A.a<B.a||(A.a==B.a&&A.b<B.b);}
}e[N];int tot,ch[N][2],p[N],v[N],bb[N],flip[N];
#define lc ch[x][0]
#define rc ch[x][1]
void update(int x) {v[x]=max(max(bb[x],v[lc]),v[rc]);}int isroot(int x) {return (ch[p[x]][0]!=x&&ch[p[x]][1]!=x);}void down(int x) {if(!flip[x]) return;swap(lc,rc); flip[lc]^=1;flip[rc]^=1;flip[x]^=1;
}void rotate(int x) {int y=p[x],z=p[y],l=(x==ch[y][1]),r=l^1;if(!isroot(y)) ch[z][y==ch[z][1]]=x; p[x]=z;ch[y][l]=ch[x][r]; p[ch[x][r]]=y;ch[x][r]=y; p[y]=x;update(y); update(x);
}void splay(int x) {static int g[N],top=0,tp;for(tp=x;!isroot(tp);tp=p[tp]) g[++top]=tp;g[++top]=tp;while(top) down(g[top--]);for(;!isroot(x);rotate(x)) {int y=p[x],z=p[y];if(!isroot(y))((x==ch[y][1])^(y==ch[z][1]))?rotate(x):rotate(y); }
}void access(int x) {for(int t=0;x;x=p[t=x]) {splay(x);ch[x][1]=t;update(x);}
}int findroot(int x) {access(x);splay(x);while(lc) x=lc;return x;
}int newroot(int x) {access(x);splay(x);flip[x]^=1;
}int qry(int x,int y) {newroot(x);access(y);splay(y);return v[y];
} void lik(int x,int y,int w) {int z=++tot;bb[z]=v[z]=w;newroot(x);p[x]=z;newroot(y);p[y]=z;
}int find(int x,int y) {if(bb[x]==y) return x;if(v[lc]==y) return find(lc,y);else return find(rc,y);
}int cut(int x) {splay(x);p[ch[x][0]]=0;p[ch[x][1]]=0;
}void work() {int ans=1e9+7;sort(e+1,e+m+1);for(int i=1;i<=m;i++) {int u=e[i].x,v=e[i].y,a=e[i].a,b=e[i].b;if(findroot(u)!=findroot(v)) lik(u,v,b);else {int tp=qry(u,v);if(b<tp) {int tpp=find(v,tp);cut(tpp);lik(u,v,b);}}if(findroot(1)==findroot(n)) {int tp=qry(1,n);ans=min(ans,a+tp);}} if(ans==1e9+7) ans=-1;printf("%d\n",ans);
}void init() {read(n); read(m);tot=n;for(int i=1;i<=m;i++) {int x,y,a,b;read(x); read(y); read(a); read(b);if(x!=y) e[++ecnt]=edge(x,y,a,b); }m=ecnt;
}int main() {
#ifdef DEBUGfreopen(".in","r",stdin);freopen(".out","w",stdout);
#endifinit();work();return 0;
}
/*
4 5
1 2 19 1
2 3 8 12
2 4 12 15
1 3 17 8
3 4 1 173 1
1 2 1 1
*/