#include<cstdio>

#include<cstring>

#include<algorithm>

using namespace std;

const int M=,inf=0x3f3f3f3f;

int read(){

    int ans=,f=,c=getchar();

    while(c<''||c>''){if(c=='-') f=-; c=getchar();}

    while(c>=''&&c<=''){ans=ans*+(c-''); c=getchar();}

    return ans*f;

}

int n,m,ans=inf;

int c[M][],fa[M],p[M];

int mx[M],v[M],rev[M];

bool isrt(int x){return c[fa[x]][]!=x&&c[fa[x]][]!=x;}

struct node{int a,b,u,v;}e[M];

bool cmp(node a,node b){return a.a<b.a;}

int find(int x){return p[x]==x?x:p[x]=find(p[x]);}

void up(int x){

    int l=c[x][],r=c[x][];

    mx[x]=x;

    if(v[mx[l]]>v[mx[x]]) mx[x]=mx[l];

    if(v[mx[r]]>v[mx[x]]) mx[x]=mx[r];

}

void down(int x){

    int l=c[x][],r=c[x][];

    if(rev[x]){

        rev[x]=; rev[l]^=; rev[r]^=;

        swap(c[x][],c[x][]);

    }

}

void rotate(int x){

    int y=fa[x],z=fa[y],l=,r=;

    if(c[y][]==x) l=,r=;

    if(!isrt(y)) c[z][c[z][]==y]=x;

    fa[y]=x; fa[x]=z; fa[c[x][r]]=y;

    c[y][l]=c[x][r]; c[x][r]=y;

    up(y); up(x);

}

int st[M],top;

void splay(int x){

    st[++top]=x; for(int i=x;!isrt(i);i=fa[i]) st[++top]=fa[i];

    while(top) down(st[top--]);

    while(!isrt(x)){

        int y=fa[x],z=fa[y];

        if(!isrt(y)){

            if(c[z][]==y^c[y][]==x) rotate(x);

            else rotate(y);

        }

        rotate(x);

    }

}

void acs(int x0){

    for(int x=x0,y=;x;splay(x),c[x][]=y,up(x),y=x,x=fa[x]);

    splay(x0);

}

void mrt(int x){acs(x); rev[x]^=;}

void link(int x,int y){mrt(x); fa[x]=y;}

void cut(int x,int y){mrt(x); acs(y); c[y][]=fa[x]=; up(y);}

int push_max(int x,int y){mrt(x); acs(y); return mx[y];}

int main()

{

    n=read(); m=read();

    for(int i=;i<=n;i++) p[i]=i;

    for(int i=;i<=m;i++) e[i].u=read(),e[i].v=read(),e[i].a=read(),e[i].b=read();

    sort(e+,e++m,cmp);

    for(int i=;i<=m;i++){

        int from=e[i].u,to=e[i].v,a=e[i].a,b=e[i].b;

        if(find(from)==find(to)){

            int now=push_max(from,to);

            if(v[now]>b){cut(now,e[now-n].v); cut(now,e[now-n].u);}

            else{

                if(find()==find(n)) ans=min(ans,a+v[push_max(,n)]);

                continue;

            }

        }

        else p[find(from)]=find(to);

        v[i+n]=b; mx[i+n]=i+n;

        link(from,i+n); link(to,i+n);

        if(find()==find(n)) ans=min(ans,a+v[push_max(,n)]);

    }

    if(ans==inf) printf("-1\n");

    else printf("%d\n",ans);

    return ;

}