#include <bits/stdc++.h>
using namespace std;
 
#define fi first
#define se second
#define pb push_back
using vi = vector <int>;
using ll = long long;
using pii = pair <int, int>;
const ll mod = 998244353;
//~ const ll mod = 1e9 + 7;
ll qpow(ll a, ll b, ll m = mod) { ll r = 1, t = a;
	for(; b; b /= 2) { if(b & 1) r = r * t % m; t = t * t % m; } return r; }

const int N = 1e5 + 11;
const int M = N * 8;

struct edge {
	int u, v, f;
	ll c;
}e[M];
int ecnt = 0;

int fe[N], ne[M];
void add(int u, int v, int f, ll c) {
	e[ecnt] = {u, v, f, c};
	ne[ecnt] = fe[u]; fe[u] = ecnt ++;
	e[ecnt] = {v, u, 0, -c};
	ne[ecnt] = fe[v]; fe[v] = ecnt ++;
}

ll dis[N];
bool inq[N];

const ll inf = 1e15;
int p[N];

int main() {
	ios :: sync_with_stdio(false);
	
	int n, m; cin >> n >> m;
	
	memset(fe, -1, sizeof fe);
	memset(ne, -1, sizeof ne);
	for(int i = 1; i <= m; i ++) {
		int u, v;
		ll c, d;
		cin >> u >> v >> c >> d;
		add(u, v, 1, c);
		add(v, u, 1, c);
		
		add(u, v, 1, d);
		add(v, u, 1, d);
	}
	
	ll ans = 0;
	for(int t : {0, 1}) {
		
		deque <int> q, rq;
		auto push = [&](int x) {
			q.push_back(x);
			rq.push_front(x);
		};
		auto pop = [&]() {
			q.pop_front();
			rq.pop_back();
		};
	 
		fill(dis, dis + n + 1, inf);
		dis[1] = 0;
		inq[1] = 1;
		push(1);
	 
		
		while(!q.empty()) {
			int x = q.front(); pop();
			inq[x] = 0;
			for(int i = fe[x]; i != -1; i = ne[i]) if(e[i].f) {
				int v = e[i].v, w = e[i].c;
				if(dis[x] + w < dis[v]) {
					dis[v] = dis[x] + w;
					p[v] = i;
					if(!inq[v]) {
						push(v);
						if(dis[q[0]] > dis[q.back()])
							q.swap(rq);
						inq[v] = 1;
					}
				}
			}
		}
		
		p[1] = -1;
		for(int i = p[n]; i != -1; i = p[e[i].u]) {
			e[i].f -= 1;
			e[i ^ 1].f += 1;
		}
		
		ans += dis[n];
	}
	cout << ans << '\n';
}