#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const ll maxn = 2e5 + 10;
ll T[maxn], L[maxn], R[maxn], C[maxn], p[maxn], dp[maxn];
int main(){
ios_base::sync_with_stdio(false);
ll n, m;
cin >> n >> m;
for (ll i = 1; i <= m; i++)
cin >> T[i] >> L[i] >> R[i] >> C[i];
for (ll i = 1; i <= m; i++)
p[i] = i;
memset(dp, -1, sizeof dp);
for (ll _ = 0; _ < m; _++){
for (ll iit = 1; iit <= m; iit++){
ll i = p[iit];
if (L[i] == 1)
dp[i] = C[i];
for (ll jit = 1; jit <= m; jit++){
ll j = p[jit];
if (abs(T[i]-T[j]) <= R[j]-L[i]+1 and dp[j] != -1)
if (dp[i] == -1 or dp[i] > dp[j] + C[i])
dp[i] = dp[j] + C[i];
}
}
}
ll answer = -1;
for (ll i = 1; i <= m; i++)
if (R[i] == n and dp[i] != -1 and (answer == -1 or answer > dp[i]))
answer = dp[i];
cout << answer << endl;
}
