#include <bits/stdc++.h>
using namespace std;
#define TRACE(x) cerr << #x << " :: " << x << endl
#define _ << " " <<
#define SZ(x) ((int)(x).size())
#define ALL(x) (x).begin(),(x).end()
#define FOR(i,a,b) for(int i=(a);i<=(b);++i)
#define RFOR(i,a,b) for(int i=(a);i>=(b);--i)
typedef long long ll;
typedef pair<ll,ll> pll;
const int mxM = 100001;
int N, M;
struct Treat {
int T, L, R, C;
} treat[mxM];
bool vis[mxM];
vector<ll> vals;
priority_queue<pll,vector<pll>,greater<pll>> pq;
struct node {
int s, e, m;
vector<pll> v;
node *l, *r;
node(int s, int e): s(s), e(e), m((s+e)/2) {
if (s != e) {
l = new node(s,m);
r = new node(m+1,e);
}
}
void update(int a, pll b) {
if (s == e) v.push_back(b);
else if (a <= m) l->update(a,b);
else r->update(a,b);
}
void build() {
if (s == e) {
sort(v.rbegin(),v.rend());
} else {
l->build();
r->build();
auto& a = l->v, b = r->v;
for (int i = 0, j = 0; i < SZ(a) || j < SZ(b);) {
if (i < SZ(a) && (j == SZ(b) || a[i] > b[j]))
v.push_back(a[i++]);
else
v.push_back(b[j++]);
}
}
//cout << s _ e << ": ";
//for (auto& x : v) { cout << x.first _ x.second << ", "; } cout << endl;
}
void proc(int a, int b, ll x, ll w) {
if (a > b) return;
if (a <= s && e <= b) {
while (SZ(v) && v.back().first <= x) {
auto i = v.back().second; v.pop_back();
if (vis[i]) continue;
vis[i] = 1;
//cout << "PUSH" _ vals[treat[i].T] _ treat[i].L _ treat[i].R << endl;
pq.push(pll(w + treat[i].C, i));
}
} else {
if (a <= m) l->proc(a,b,x,w);
if (b > m) r->proc(a,b,x,w);
}
}
} *root1, *root2;
int main() {
ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
cin >> N >> M;
FOR(i,1,M){
int T, L, R, C;
cin >> T >> L >> R >> C;
treat[i] = {T,L,R,C};
vals.push_back(T);
}
sort(ALL(vals));
vals.resize(unique(ALL(vals))-vals.begin());
root1 = new node(0,SZ(vals)-1);
root2 = new node(0,SZ(vals)-1);
memset(vis,0,sizeof vis);
FOR(i,1,M){
auto& t = treat[i];
t.T = lower_bound(ALL(vals),t.T)-vals.begin();
//cout << i _ t.T _ t.L+vals[t.T]-1 _ t.L-vals[t.T]-1 << endl;
//cout << i _ t.T _ t.R+vals[t.T] _ t.R-vals[t.T]-1 << endl;
if (t.L == 1) {
vis[i] = 1;
pq.push(pll(t.C,i));
} else {
root1->update(t.T, pll(t.L+vals[t.T]-1,i));
root2->update(t.T, pll(t.L-vals[t.T]-1,i));
}
}
root1->build();
root2->build();
while (!pq.empty()) {
auto [w, u] = pq.top(); pq.pop();
auto t = treat[u];
//TRACE(u _ vals[t.T] _ t.L _ t.R _ w);
if (t.R == N) {
cout << w << '\n';
return 0;
}
root1->proc(t.T, SZ(vals)-1, t.R+vals[t.T], w);
root2->proc(0, t.T-1, t.R-vals[t.T], w);
}
cout << -1 << '\n';
}
