#include<cstdio>
#include<vector>
#include<algorithm>
using namespace std;
int n,m,cnt;
int to[200005],vala[200005],valb[200005],nxt[200005],h[200005];
void add(int u,int v,int a,int b){
    to[++cnt]=v;
    vala[cnt]=a;
    valb[cnt]=b;
    nxt[cnt]=h[u];
    h[u]=cnt;
}
struct node{
    int u,v,a,b;
    bool operator <(const node &x) const{
        return b<x.b;
    }
};
vector<node>edge;
int ans=0x3f3f3f3f;
int fa[50005];
int Find(int x){
    if(x==fa[x])return x;
    return fa[x]=Find(fa[x]);
}
int main(){
    freopen("magicalforest.in","r",stdin);
    freopen("magicalforest.out","w",stdout);
    scanf("%d%d",&n,&m);
    for(int i=1;i<=m;i++){
        int u,v,a,b;
        scanf("%d%d%d%d",&u,&v,&a,&b);
        edge.push_back({u,v,a,b});
        edge.push_back({v,u,a,b});
    }
    sort(edge.begin(),edge.end());
    int ans=0x3f3f3f3f;
    for(auto x:edge){
        for(int i=1;i<=n;i++)fa[i]=i;
        bool flag=0;
        int num=0;
        for(auto y:edge){
            if(y.a>x.a)continue;
            fa[Find(y.u)]=Find(y.v);
            num=max(num,y.b);
            if(Find(1)==Find(n)){
                flag=1;
                break;
            }
        }
        if(flag)ans=min(ans,x.a+num);
    }
    if(ans!=0x3f3f3f3f)printf("%d",ans);
    else printf("-1");
    return 0;
}