#include <bits/stdc++.h>

using namespace std;
using ll = long long;

struct Segment {
    int t, l, r, w;
};

constexpr ll inf = 3e18;

template<typename T, typename O>
bool ckmin(T &a, const O &b) { return (b < a) ? a = b, 1 : 0; }

template<typename T, typename O>
bool ckmax(T &a, const O &b) { return (b > a) ? a = b, 1 : 0; }

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int n, m;
    cin >> n >> m;

    vector<Segment> s(m);

    for (auto &[t, l, r, w] : s) {
        cin >> t >> l >> r >> w;
    }

    sort(s.begin(), s.end(), [&](const auto &x, const auto &y) {
        return array{x.r - x.t, y.l} < array{y.r - y.t, y.l};
    });

    vector<ll> dp(m, inf);

    bool updated = true;

    while (updated) {
        updated = false;

        for (int i = 0; i < m; ++i) {
            if (s[i].l == 1) {
                updated |= ckmin(dp[i], s[i].w);
                continue;
            }
            for (int j = 0; j < m; ++j) {
                if (s[j].r - s[i].l + 1 >= abs(s[i].t - s[j].t)) {
                    updated |= ckmin(dp[i], dp[j] + s[i].w);
                }
            }
        }
    }

    ll ans = inf;

    for (int i = 0; i < m; ++i) {
        if (s[i].r == n) {
            ans = min(ans, dp[i]);
        }
    }

    if (ans == inf) {
        cout << "-1\n";
    } else {
        cout << ans << '\n';
    }

    return 0;
}