#include <iostream>
#include<vector>
#define int long long
using namespace std;
vector<vector<int>> g[205];
bool r1[205] = { 0 }, rn[205] = { 0 }, c1[205] = { 0 }, cn[205] = { 0 };
bool dom[50005] = { 0 };
vector<int> vis(205, 0), path;
vector<vector<int>> e;
void dfs1(int node, int s, int n) {
vis[node] = 1; //fill c1, cn, r1, rn
if (s == 1) r1[node] = 1;
else if (s == n) rn[node] = 1;
if (node == 1) c1[s] = 1;
else if (node == n) cn[node] = 1;
for (auto x : g[node])
if (!vis[x[0]])
dfs1(x[0], s, n);
}
bool dfs2(int node, int t) {
vis[node] = 1;
if (node == t) return 1;
for (auto x : g[node])
if (!vis[x[0]]) {
path.push_back(x[2]);
if (dfs2(x[0], t))
return 1;
path.pop_back();
}
return 0;
}
bool dfs3(int node, int t, int l) {
vis[node] = 1;
if (node == t) return 1;
for (auto x : g[node])
if (!vis[x[0]] && (x[2] != l))
if (dfs3(x[0], t, l))
return 1;
return 0;
}
int32_t main()
{
int n, m; cin >> n >> m;
for (int i = 0; i < m; ++i) {
int u, v, c, d; cin >> u >> v >> c >> d;
g[u].push_back({ v, d, i });
e.push_back({ u, v, d, i });
}
for (int i = 1; i <= n; ++i) {
dfs1(i, i, n);
vis.assign(n + 1, 0);
}
if (cn[1] && c1[n]) { cout << 0; return 0; }
int s = 0;
if (cn[1]) s = 1;
else if (c1[n]) s = n;
int o = ((s == 1) ? n : 1);
if (s) {
dfs2(s, o), vis.assign(n + 1, 0);
for (auto x : path) {
if (!dfs3(s, o, x))
dom[x] = 1; //this edge dominates s-t
vis.assign(n + 1, 0);
}
}
int ans = 1e17;
for(int i = 0; i < m; ++i)
if (!dom[i]) {
int u = e[i][0], v = e[i][1];
if ((s == 0) || (o == n))
if ((!rn[v]) || (!c1[u]))
continue;
if(o != n)
if ((!r1[v]) || (!cn[u]))
continue;
ans = min(ans, e[i][2]);
}
cout << ((ans == 1e17)? -1: ans);
}
