#include <bits/stdc++.h>
using namespace std;

#ifdef DEBUG
auto&operator<<(auto&o,pair<auto,auto>p){return o<<"("<<p.first<<", "<<p.second<<")";}
auto operator<<(auto&o,auto x)->decltype(x.end(),o){o<<"{";int i=0;for(auto e:x)o<<","+!i++<<e;return o<<"}";}
#define debug(X...)cerr<<"["#X"]: ",[](auto...$){((cerr<<$<<"; "),...)<<endl;}(X)
#else
#define debug(...){}
#endif

#define ll long long
#define ld long double
#define endl '\n'
#define st first
#define nd second
#define pb push_back
#define sz(x) (int)(x).size()
#define all(x) (x).begin(), (x).end()
#define FOR(i,l,r) for(int i=(l);i<=(r);i++)
#define ROF(i,r,l) for(int i=(r);i>=(l);i--)
int inf=1000000007;
ll infl=1000000000000000007;
ll mod=1000000007;

const int N=100007;

int t[N],l[N],r[N];
ll DP[N],c[N];
bool odw[N];

signed main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    int n,m;
    cin>>n>>m;
    FOR(i,1,m)
    {
		cin>>t[i]>>l[i]>>r[i]>>c[i];
		DP[i]=infl;
		if(l[i]==1) DP[i]=c[i];
	}
	ll ans=infl;
	FOR(k,1,n)
	{
		ll mn=infl+1;
		int i;
		FOR(j,1,m) 
		{
			if(!odw[j]&&DP[j]<mn)
			{
				mn=DP[j];
				i=j;
			}
		}
		odw[i]=1;
		debug(i,DP[i]);
		FOR(j,1,m) 
		{
			if(t[j]<=t[i])
			{
				if(r[i]-(t[i]-t[j])>=l[j]-1) DP[j]=min(DP[j],DP[i]+c[j]);
			}
			else
			{
				if(r[i]-(t[j]-t[i])>=l[j]-1) DP[j]=min(DP[j],DP[i]+c[j]);
			}
		}
		if(r[i]==n) ans=min(ans,DP[i]);
	}
	if(ans==infl) cout<<-1<<endl;
	else cout<<ans<<endl;
    return 0;
}