#include<bits/stdc++.h>
#define int long long
#define rep(i,a,b) for(int i=(a);i<=(b);i++)
#define per(i,a,b) for(int i=(a);i>=(b);i--)
#define fi first
#define se second
#define eb emplace_back
#define popc __builtin_popcount
#define clz __builtin_clz
#define ctz __builtin_ctz
using namespace std;
typedef pair<int,int> pii;
typedef vector<int> vi;
typedef vector<pii> vp;
typedef long double ld;
typedef unsigned long long ull;
typedef long long i64;
typedef __int128 i128;

int read() {
  int x=0,w=1; char c=getchar(); 
  while(!isdigit(c)) {if(c=='-') w=-1; c=getchar();}
  while(isdigit(c)) {x=x*10+(c-'0'); c=getchar();}
  return x*w;
}

const int N=5e6+9,inf=0x3f3f3f3f3f3f3f3f;
int n,m,S,T,tot,rt1,rt2,ls[N],rs[N],b[N],k,t[N],l[N],r[N],c[N],d[N],vst[N];
vi e[N];
struct node {int t,l,r,id;} a[N];
bool cmp1(const node &a,const node &b) {
  return a.t==b.t?a.r<b.r:a.t<b.t;
}
bool cmp2(const node &a,const node &b) {
  return a.t==b.t?a.l>b.l:a.t<b.t;
}

void add(int p,int &q,int l,int r,int x,int z,int w) {
  q=++tot; if(p) {if(w) e[q].eb(p); else e[p].eb(q);}
  if(l==r) {if(w) e[q].eb(z); else e[z].eb(q); return;}
  int mid=l+r>>1;
  if(x<=mid) {
    add(ls[p],ls[q],l,mid,x,z,w); rs[q]=rs[p];
  } else {
    add(rs[p],rs[q],mid+1,r,x,z,w); ls[q]=ls[p];
  }
  if(ls[q]) {if(w) e[q].eb(ls[q]); else e[ls[q]].eb(q);}
  if(rs[q]) {if(w) e[q].eb(rs[q]); else e[rs[q]].eb(q);}
}
void cov(int p,int l,int r,int x,int y,int z,int w) {
  if(!p) return;
  if(l==x&&r==y) {if(w) e[z].eb(p); else e[p].eb(z); return;}
  int mid=l+r>>1;
  if(y<=mid) cov(ls[p],l,mid,x,y,z,w);
  else if(x>mid) cov(rs[p],mid+1,r,x,y,z,w);
  else cov(ls[p],l,mid,x,mid,z,w), cov(rs[p],mid+1,r,mid+1,y,z,w);
}
void dijkstra() {
  rep(i,1,tot) d[i]=inf; d[S]=0;
  priority_queue<pii>q; q.push(pii(0,S));
  while(!q.empty()) {
    int u=q.top().se; q.pop();
    if(vst[u]) continue; vst[u]=1;
    for(int v:e[u]) if(d[v]>d[u]+c[v]) {
      d[v]=d[u]+c[v]; q.push(pii(-d[v],v));
    }
  }
}

signed main() {
  n=read(), m=read();
  rep(i,1,m) {
    a[i].t=read(), a[i].id=i;
    a[i].l=read(), a[i].r=read(), c[i]=read();
  }
  tot=m;
  sort(a+1,a+m+1,cmp1); k=0;
  rep(i,1,m) b[++k]=a[i].r+a[i].t;
  rep(i,1,m) b[++k]=a[i].l+a[i].t-1;
  sort(b+1,b+k+1); k=unique(b+1,b+k+1)-b-1;
  rep(i,1,m) {
    int x=lower_bound(b+1,b+k+1,a[i].r+a[i].t)-b;
    int y=lower_bound(b+1,b+k+1,a[i].l+a[i].t-1)-b;
    cov(rt1,1,k,y,k,a[i].id,0);
    add(rt1,rt1,1,k,x,a[i].id,0);
  }
  sort(a+1,a+m+1,cmp2); k=0;
  rep(i,1,m) b[++k]=a[i].l-a[i].t;
  rep(i,1,m) b[++k]=a[i].r-a[i].t+1;
  sort(b+1,b+k+1); k=unique(b+1,b+k+1)-b-1;
  rep(i,1,m) {
    int x=lower_bound(b+1,b+k+1,a[i].l-a[i].t)-b;
    int y=lower_bound(b+1,b+k+1,a[i].r-a[i].t+1)-b;
    cov(rt2,1,k,1,y,a[i].id,1);
    add(rt2,rt2,1,k,x,a[i].id,1);
  }
  S=++tot, T=++tot;
  rep(i,1,m) {
    if(a[i].l==1) e[S].eb(a[i].id);
    if(a[i].r==n) e[a[i].id].eb(T);
  }
  dijkstra();
  if(d[T]==inf) puts("-1");
  else printf("%lld\n",d[T]);
  return 0;
}