#include <bits/stdc++.h>
using namespace std;
//#include <atcoder/all>
//using namespace atcoder;
using ll=long long;
using Graph=vector<vector<pair<int,int>>>;
#define MAX 200003
#define MOD 1000000007
#define INF 1000000000000000000

int main(){
  int N,M;
  cin>>N>>M;
  vector<int> u(M),v(M);
  vector<ll> c(M),d(M);
  for(int i=0;i<M;i++){
    cin>>u[i]>>v[i]>>c[i]>>d[i];
    u[i]--;
    v[i]--;
  }

  Graph G(N);
  for(int i=0;i<M;i++){
    G[u[i]].push_back(make_pair(v[i],i));
    G[v[i]].push_back(make_pair(u[i],i));
  }

  vector<ll> dist(N,INF);
  dist[0]=0;
  priority_queue<pair<ll,int>,vector<pair<ll,int>>,greater<pair<ll,int>>> pq;
  pq.push(make_pair(dist[0],0));
  while(!pq.empty()){
    int v=pq.top().second;
    ll l=pq.top().first;
    pq.pop();
    if(l>dist[v]){
      continue;
    }
    for(auto p:G[v]){
      int nv=p.first;
      int e=p.second;
      if(dist[v]+c[e]<dist[nv]){
        dist[nv]=dist[v]+c[e];
        pq.push(make_pair(dist[nv],nv));
      }
    }
  }

  int x=N-1;
  vector<bool> used(M,false);
  while(x!=0){
    for(auto p:G[x]){
      int nv=p.first;
      int e=p.second;
      if(dist[x]==dist[nv]+c[e]){
        x=nv;
        used[e]=true;
        break;
      }
    }
  }

  ll ans=dist[N-1];
  for(int i=0;i<N-1;i++){
    dist[i]=INF;
  }
  dist[N-1]=0;
  pq.push(make_pair(dist[N-1],N-1));
  while(!pq.empty()){
    int v=pq.top().second;
    ll l=pq.top().first;
    pq.pop();
    if(l>dist[v]){
      continue;
    }
    for(auto p:G[v]){
      int nv=p.first;
      int e=p.second;
      if(used[e]==true){
        if(dist[v]+d[e]<dist[nv]){
          dist[nv]=dist[v]+d[e];
          pq.push(make_pair(dist[nv],nv));
        }
      }else{
        if(dist[v]+c[e]<dist[nv]){
          dist[nv]=dist[v]+c[e];
          pq.push(make_pair(dist[nv],nv));
        }
      }
    }
  }
  ans+=dist[0];
  cout<<ans<<endl;
}