#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;

const int N = 50005, M = 100005, INF = 0x3f3f3f3f;

int n, m, d[N], hh, tt, q[N], ans = INF;

bool vis[N];

struct Edge{
	int u, v, a, b;
	bool operator < (const Edge &z) const {
		return a < z.a;
	}
} g[M];

int head[N], numE = 0;

struct E{
	int next, v, w;
} e[M << 1];

void inline add(int u, int v, int w) {
	e[++numE] = (E) { head[u], v, w };
	head[u] = numE;
}

void spfa() {
	while (hh != tt) {
		int u = q[hh++]; vis[u] = false;
		if (hh == N) hh = 0;
		for (int i = head[u]; i; i = e[i].next) {
			int v = e[i].v;
			if (max(e[i].w, d[u]) < d[v]) {
				d[v] = max(e[i].w, d[u]);
				if (!vis[v]) {
					q[tt++] = v, vis[v] = true;
					if (tt == N) tt = 0;
				}
			}
		}
	}
}

int main() {
	memset(d, 0x3f, sizeof d);
	d[1] = 0;
	scanf("%d%d", &n, &m);
	for (int i = 1; i <= m; i++) 
		scanf("%d%d%d%d", &g[i].u, &g[i].v, &g[i].a, &g[i].b);
	sort(g + 1, g + 1 + m);
	for (int i = 1; i <= m; i++) {
		add(g[i].u, g[i].v, g[i].b), add(g[i].v, g[i].u, g[i].b);
		hh = 0, tt = 2;
		q[0] = g[i].u, q[1] = g[i].v;
		vis[q[0]] = vis[q[1]] = true;
		spfa();
		if (d[n] != INF) ans = min(ans, g[i].a + d[n]);
	}
	if (ans == INF) puts("-1");
	else printf("%d\n", ans);
	return 0;
}