#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int inf = 1e9 + 7;
int main() {
ios::sync_with_stdio(0);
cin.tie(0);
int n, m;
cin >> n >> m;
vector <vector <pair <int, int> > > g(n);
for (int i = 0; i < m; i++) {
int a, b, c, p;
cin >> a >> b >> c >> p;
a--, b--;
g[a].push_back({b, c});
g[b].push_back({a, c});
}
vector <vector <pair <int, int> > > cg(n);
map <int, int> color_cnt;
for (int i = 0; i < n; i++) {
vector <pair <int, int> > cols;
for (auto [v, c] : g[i]) {
cols.push_back({c, v});
color_cnt[c]++;
}
sort(cols.begin(), cols.end());
for (int j = 0; j < (int) cols.size(); j++) {
bool alone = true;
if (j >= 0 && cols[j - 1].first == cols[j].first) {
alone = false;
}
if (j + 1 < (int) cols.size() && cols[j + 1].first == cols[j].first) {
alone = false;
}
if (alone) {
cg[i].push_back({cols[j].second, 0});
} else {
cg[i].push_back({cols[j].second, 1});
}
}
for (int j = 1; j < (int) cols.size(); j++) {
if (cols[j].first == cols[j - 1].first && color_cnt[cols[j].first] == 2) {
cg[cols[j - 1].second].push_back({cols[j].second, 1});
cg[cols[j].second].push_back({cols[j - 1].second, 1});
}
}
for (auto [v, c] : g[i]) {
color_cnt[c]--;
}
}
vector <int> d(n, inf);
deque <int> q;
q.push_front(0);
d[0] = 0;
while (!q.empty()) {
int v = q.front();
q.pop_front();
for (auto [to, c] : cg[v]) {
if (d[to] > d[v] + c) {
d[to] = d[v] + c;
if (c == 0) {
q.push_front(to);
} else {
q.push_back(to);
}
}
}
}
cout << (d[n - 1] == inf ? -1 : d[n - 1]) << '\n';
return 0;
}
