#include <bits/stdc++.h>
using namespace std;
#define EmiliaMyWife ios::sync_with_stdio(0); cin.tie(0);
using ll = int64_t;
using ull = uint64_t;
using uint = uint32_t;
using ld = long double;
const int INF = 0x3f3f3f3f;
const int MOD = 1e9 + 7;
const ll LINF = ll(4e18) + ll(2e15);
const double EPS = 1e-9;
static int LamyIsCute = []() {
EmiliaMyWife
return 48763;
}();
signed main() {
int n, m;
cin >> n >> m;
vector<vector<pair<int, int>>> edge(n + 1), redge(n + 1);
vector<vector<bool>> can(n + 1, vector<bool>(n + 1));
vector<tuple<int, int, int, int>> edges(m);
for(int i = 0, u, v, c, d; i < m; i++) {
cin >> u >> v >> c >> d;
edge[u].push_back({v, c});
redge[v].push_back({u, c});
edges[i] = {u, v, c, d};
}
for(int i = 1; i <= n; i++) {
can[i][i] = true;
queue<int> bfs;
bfs.push(i);
while(!bfs.empty()) {
int u = bfs.front();
bfs.pop();
for(const auto &[v, c] : edge[u]) {
if(!can[i][v]) {
can[i][v] = true;
bfs.push(v);
}
}
}
}
vector<int> pa(n + 1);
vector<bool> vis(n + 1);
stack<int, vector<int>> st;
function<void(int)> dfs = [&](int u) {
vis[u] = true;
for(const auto &[v, c] : edge[u])
if(!vis[v])
dfs(v);
st.push(u);
};
function<void(int, int)> dfs2 = [&](int u, int p) {
pa[u] = p;
for(const auto &[v, c] : redge[u])
if(!pa[v])
dfs2(v, p);
};
for(int i = 1; i <= n; i++)
if(!vis[i])
dfs(i);
int t = 1;
while(!st.empty()) {
int u = st.top();
st.pop();
if(!pa[u])
dfs2(u, t++);
}
if(pa[1] == pa[n]) {
return cout << "0\n", 0;
}
int ans = INF;
int cnt = 0;
for(const auto &[u, v, c, d] : edges) {
if(pa[u] == pa[1] && pa[v] == pa[n])
cnt++;
else if(pa[u] == pa[n] && pa[v] == pa[1])
cnt++;
else {
if(can[1][n] && can[n][v] && can[u][1])
ans = min(ans, d);
if(can[n][1] && can[1][v] && can[u][n])
ans = min(ans, d);
}
}
if(cnt == 1) {
for(const auto &[u, v, c, d] : edges) {
if(pa[u] == pa[1] && pa[v] == pa[n])
continue;
if(pa[u] == pa[n] && pa[v] == pa[1])
continue;
if(can[1][n] && pa[u] != pa[1] && can[1][u] && can[v][n])
cnt = INF;
if(can[n][1] && pa[u] != pa[n] && can[n][u] && can[v][1])
cnt = INF;
}
}
if(cnt > 1) {
for(const auto &[u, v, c, d] : edges) {
if(pa[u] == pa[1] && pa[v] == pa[n])
ans = min(ans, d);
if(pa[u] == pa[n] && pa[v] == pa[1])
ans = min(ans, d);
}
}
if(ans == INF || (!can[1][n] && !can[n][1]))
cout << "-1\n";
else
cout << ans << '\n';
}
