#pragma GCC target("avx2")
#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")
#include <bits/stdc++.h>
using namespace std;
#define DEBUG
#ifdef DEBUG
template <class T, class U>
ostream &operator<<(ostream &os, const pair<T, U> &p) {
    os << '(' << p.first << ',' << p.second << ')';
    return os;
}
template <class T> ostream &operator<<(ostream &os, const vector<T> &v) {
    os << '{';
    for(int i = 0; i < (int)v.size(); i++) {
        if(i) { os << ','; }
        os << v[i];
    }
    os << '}';
    return os;
}
void debugg() { cerr << endl; }
template <class T, class... Args>
void debugg(const T &x, const Args &... args) {
    cerr << " " << x;
    debugg(args...);
}
#define debug(...)                                                             \
    cerr << __LINE__ << " [" << #__VA_ARGS__ << "]: ", debugg(__VA_ARGS__)
#define dump(x) cerr << __LINE__ << " " << #x << " = " << (x) << endl
#else
#define debug(...) (void(0))
#define dump(x) (void(0))
#endif
using namespace std;
typedef long long ll;
typedef vector<ll> vl;
typedef vector<vl> vvl;
typedef vector<char> vc;
typedef vector<string> vs;
typedef vector<bool> vb;
typedef vector<double> vd;
typedef pair<ll,ll> P;
typedef pair<int,int> pii;
typedef vector<P> vpl;
typedef tuple<ll,ll,ll> tapu;
#define rep(i,n) for(int i=0; i<(n); i++)
#define REP(i,a,b) for(int i=(a); i<(b); i++)
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
const int inf = 1<<30;
const ll linf = 1LL<<62;
const int MAX = 510000;
int dy[8] = {0,-1,0,1,1,-1,-1,1};
int dx[8] = {-1,0,1,0,1,-1,1,-1};
const double pi = acos(-1);
const double eps = 1e-7;
template<typename T1,typename T2> inline bool chmin(T1 &a,T2 b){
	if(a>b){
		a = b; return true;
	}
	else return false;
}
template<typename T1,typename T2> inline bool chmax(T1 &a,T2 b){
	if(a<b){
		a = b; return true;
	}
	else return false;
}
template<typename T> inline void print(T &a){
    int sz = a.size();
    for(auto itr = a.begin(); itr != a.end(); itr++){
		cout << *itr;
        sz--;
        if(sz) cout << " ";
	}
    cout << "\n";
}
template<typename T1,typename T2> inline void print2(T1 a, T2 b){
	cout << a << " " << b << "\n";
}
template<typename T1,typename T2,typename T3> inline void print3(T1 a, T2 b, T3 c){
	cout << a << " " << b << " " << c << "\n";
}
void mark() {cout << "#" << "\n";}
ll pcount(ll x) {return __builtin_popcountll(x);}
//const int mod = 1e9 + 7;
const int mod = 998244353;

struct edge{
	ll to, c, d, id, mode;
};


int main(){
	ll n,m; cin >> n >> m;
	vector<vector<edge>> G(n);
	rep(i,m){
		ll u,v,c,d; cin >> u >> v >> c >> d; u--; v--;
		G[u].push_back(edge{v,c,d,i,0});
		G[v].push_back(edge{u,c,d,i,0});
	}
	priority_queue<P,vector<P>,greater<P>> pq;
	vl d(n,linf);
	d[0] = 0;
	vl pre(n);
	pq.emplace(0,0);
	while(!pq.empty()){
		P p = pq.top(); pq.pop();
		ll u = p.second;
		if(d[u] < p.first) continue;
		for(auto v : G[u]){
			if(chmin(d[v.to], d[u] + v.c)){
				pre[v.to] = v.id;
				pq.emplace(d[v.to], v.to);
			}
		}
	}
	ll ans = d[n-1];
	ll now = n-1;
	while(now > 0){
		for(auto &v : G[now]){
			if(v.id == pre[now]){
				v.mode = 1;
				now = v.to;
				break;
			}
		}
	}
	rep(i,n) d[i] = linf; d[n-1] = 0;
	pq.emplace(0,n-1);
	while(!pq.empty()){
		P p = pq.top(); pq.pop();
		ll u = p.second;
		if(d[u] < p.first) continue;
		for(auto v : G[u]){
			ll cost = v.mode == 0 ? v.c : v.d;
			if(chmin(d[v.to], cost + d[u])){
				pq.emplace(d[v.to], v.to);
			}
		}
	}
	ans += d[0];
	cout << ans << "\n";
}