#include<iostream>
#include<cstdio>
#include<algorithm>
#include<cmath>
#include<cstring>
#include<vector>
using namespace std;
typedef long long ll;
inline int read()
{int x=0,f=1; char ch=getchar();while(ch<'0'||ch>'9') { if(ch=='-') f=-1; ch=getchar(); }while(ch>='0'&&ch<='9') { x=(x<<1)+(x<<3)+(ch^48); ch=getchar(); }return x*f;
}
const int N=4e5+7,INF=1e9+7;
int n,m,ANS=INF;
struct dat{int x,y,a,b;inline bool operator < (const dat &tmp) const {return a<tmp.a;}
}d[N];
int c[N][2],fa[N],t[N],val[N];
//把边化成点后,t维护点权最大的点的编号，val[x]存点x的b值
//边的编号为n+1到n+m
bool rev[N];
inline void pushdown(int x)
{if(!rev[x]||!x) return;int &lc=c[x][0],&rc=c[x][1];rev[x]=0; swap(lc,rc);if(lc) rev[lc]^=1;if(rc) rev[rc]^=1;
}
inline void rever(int x) { rev[x]^=1; pushdown(x); }
inline void pushup(int x)
{t[x]=x;if(val[ t[c[x][0]] ] > val[t[x]]) t[x]=t[c[x][0]];if(val[ t[c[x][1]] ] > val[t[x]]) t[x]=t[c[x][1]];
}
inline bool notroot(int x) { return (c[fa[x]][0]==x)|(c[fa[x]][1]==x); }
inline void rotate(int x)
{int y=fa[x],z=fa[y],d=(c[y][1]==x);if(notroot(y)) c[z][c[z][1]==y]=x;fa[x]=z; fa[y]=x; fa[c[x][d^1]]=y;c[y][d]=c[x][d^1]; c[x][d^1]=y;pushup(y); pushup(x);
}
inline void push_rev(int x)
{if(notroot(x)) push_rev(fa[x]);else pushdown(x);pushdown(c[x][0]); pushdown(c[x][1]);
}
inline void splay(int x)
{push_rev(x);while(notroot(x)){int y=fa[x],z=fa[y];if(notroot(y)){if(c[y][0]==x ^ c[z][0]==y) rotate(x);else rotate(y);}rotate(x);}
}
inline void access(int x)
{for(int y=0;x;y=x,x=fa[x])splay(x),c[x][1]=y,pushup(x);
}
inline void makeroot(int x) { access(x); splay(x); rever(x); }
inline int findroot(int x)
{access(x); splay(x); pushdown(x);while(c[x][0]) pushdown(c[x][0]),x=c[x][0];splay(x);return x;
}
inline int split(int x,int y) { makeroot(x); access(y); splay(y); return t[y]; }//提取一段路径上点权最大的点的编号
inline void link(int x,int y) { makeroot(x); if(findroot(y)!=x) fa[x]=y; }
inline void cut(int x,int y)
{makeroot(x);if(findroot(y)!=x||fa[y]!=x||c[y][0]) return;c[x][1]=fa[y]=0; pushup(x);
}
inline void query(int a)//更新答案
{if(findroot(1)==findroot(n))//如果在同一颗树上
    {int w=split(1,n);ANS=min(ANS,a+val[w]);}
}
inline void insert(int i)//加入边
{int x=d[i].x,y=d[i].y,a=d[i].a,b=d[i].b; bool flag=1;if(findroot(x)==findroot(y))//如果原本已经是一颗树
    {int w=split(x,y);if(val[w]>b) cut(w,d[w-n].x),cut(w,d[w-n].y);//如果b更小才cutelse flag=0;//否则不连边
    }if(flag) link(n+i,x),link(n+i,y),query(a);//连边并更新ANS
}
int main()
{n=read(),m=read();for(int i=1;i<=m;i++)d[i].x=read(),d[i].y=read(),d[i].a=read(),d[i].b=read();sort(d+1,d+m+1);for(int i=1;i<=m;i++) val[n+i]=d[i].b;for(int i=1;i<=m;i++) insert(i);printf("%d",ANS <1e9 ? ANS : -1);return 0;
}