#include <bits/stdc++.h>
#define fi first
#define se second
#define mp make_pair
#define Sz(x) (int)x.size()
using namespace std;
const int N = 205;
const int inf = 1e9;
int n, m, cnt[N][N], used[N], val[N][N];
vector <int> g[N];
void dfs(int v) {
used[v] = 1;
for (auto to : g[v]) {
if (!used[to])
dfs(to);
}
}
void solve() {
cin >> n >> m;
vector <pair<int,int>> save;
for (int i = 1; i <= n; i++) {
for (int j = 1; j <= n; j++) {
val[i][j] = inf;
}
}
for (int i = 1; i <= m; i++) {
int u, v, c, d;
cin >> u >> v >> c >> d;
g[u].push_back(v);
cnt[u][v]++;
val[u][v] = min(val[u][v], d);
if (cnt[u][v] == 1) save.push_back(mp(u, v));
}
int ok1 = 0, ok2 = 0;
dfs(1);
if (used[n]) ok1 = 1;
for (int i = 1; i <= n; i++) used[i] = 0;
dfs(n);
if (used[1]) ok2 = 1;
if (ok1 && ok2) {
cout << 0;
return;
}
int ans = inf;
for (auto [x, y] : save) {
for (int i = 1; i <= n; i++) g[i].clear();
cnt[x][y]--;
g[y].push_back(x);
for (int i = 1; i <= n; i++) {
for (int j = 1; j <= n; j++) {
if (cnt[i][j]) g[i].push_back(j);
}
}
cnt[x][y]++;
for (int i = 1; i <= n; i++) used[i] = 0;
int ok1 = 0, ok2 = 0;
dfs(1);
if (used[n]) ok1 = 1;
for (int i = 1; i <= n; i++) used[i] = 0;
dfs(n);
if (used[1]) ok2 = 1;
if (ok1 && ok2) {
ans = min(ans, val[x][y]);
}
}
if (ans == inf) cout << -1;
else cout << ans;
}
signed main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
int tt = 1;
// cin >> tt;
while (tt--) {
solve();
// cout << '\n';
}
}
