#define DEBUG 0
#include <bits/stdc++.h>
using namespace std;
#if DEBUG
// basic debugging macros
int __i__,__j__;
#define printLine(l) for(__i__=0;__i__<l;__i__++){cout<<"-";}cout<<endl
#define printLine2(l,c) for(__i__=0;__i__<l;__i__++){cout<<c;}cout<<endl
#define printVar(n) cout<<#n<<": "<<n<<endl
#define printArr(a,l) cout<<#a<<": ";for(__i__=0;__i__<l;__i__++){cout<<a[__i__]<<" ";}cout<<endl
#define print2dArr(a,r,c) cout<<#a<<":\n";for(__i__=0;__i__<r;__i__++){for(__j__=0;__j__<c;__j__++){cout<<a[__i__][__j__]<<" ";}cout<<endl;}
#define print2dArr2(a,r,c,l) cout<<#a<<":\n";for(__i__=0;__i__<r;__i__++){for(__j__=0;__j__<c;__j__++){cout<<setw(l)<<setfill(' ')<<a[__i__][__j__]<<" ";}cout<<endl;}
// advanced debugging class
// debug 1,2,'A',"test";
class _Debug {
public:
template<typename T>
_Debug& operator,(T val) {
cout << val << endl;
return *this;
}
};
#define debug _Debug(),
#else
#define printLine(l)
#define printLine2(l,c)
#define printVar(n)
#define printArr(a,l)
#define print2dArr(a,r,c)
#define print2dArr2(a,r,c,l)
#define debug
#endif
// define
#define MAX_VAL 999999999
#define MAX_VAL_2 999999999999999999LL
#define EPS 1e-6
#define mp make_pair
#define pb push_back
// typedef
typedef unsigned int UI;
typedef long long int LLI;
typedef unsigned long long int ULLI;
typedef unsigned short int US;
typedef pair<int,int> pii;
typedef pair<LLI,LLI> plli;
typedef vector<int> vi;
typedef vector<LLI> vlli;
typedef vector<pii> vpii;
typedef vector<plli> vplli;
// ---------- END OF TEMPLATE ----------
struct pro { int t,l,r,c; };
bool comp(pro a,pro b) {
return a.t < b.t;
}
pro p[100000];
vpii adjList[3000000];
pii sorted[100000];
int bit[100001],num;
LLI dist[3000000];
priority_queue<pair<LLI,int> > H;
int main() {
int i;
int N,M;
scanf("%d %d",&N,&M);
for (i = 0; i < M; i++) scanf("%d %d %d %d",&p[i].t,&p[i].l,&p[i].r,&p[i].c),p[i].l--,p[i].r--;
sort(p,p+M,comp);
int j;
for (i = 0; i < M; i++) {
if (p[i].l == 0) adjList[0].pb(mp(i+2,p[i].c));
if (p[i].r == N-1) adjList[i+2].pb(mp(1,0));
sorted[i] = mp(p[i].l-p[i].t,i);
}
num = M+2;
sort(sorted,sorted+M);
for (i = 1; i <= M; i++) bit[i] = num++;
for (i = 0; i < M; i++) {
int x = lower_bound(sorted,sorted+M,mp(p[i].l-p[i].t,i))-sorted;
for (j = x+1; j <= M; j += j & (-j)) {
adjList[num].pb(mp(bit[j],0)),adjList[num].pb(mp(i+2,p[i].c));
bit[j] = num++;
}
x = upper_bound(sorted,sorted+M,mp(p[i].r-p[i].t+1,M))-sorted-1;
for (j = x+1; j > 0; j -= j & (-j)) adjList[i+2].pb(mp(bit[j],0));
}
for (i = 0; i < M; i++) sorted[i] = mp(p[i].l+p[i].t,i);
sort(sorted,sorted+M);
for (i = 1; i <= M; i++) bit[i] = num++;
for (i = M-1; i >= 0; i--) {
int x = lower_bound(sorted,sorted+M,mp(p[i].l+p[i].t,i))-sorted;
for (j = x+1; j <= M; j += j & (-j)) {
adjList[num].pb(mp(bit[j],0)),adjList[num].pb(mp(i+2,p[i].c));
bit[j] = num++;
}
x = upper_bound(sorted,sorted+M,mp(p[i].r+p[i].t+1,M))-sorted-1;
for (j = x+1; j > 0; j -= j & (-j)) adjList[i+2].pb(mp(bit[j],0));
}
for (i = 0; i < num; i++) dist[i] = -1;
dist[0] = 0,H.push(mp(0,0));
while (!H.empty()) {
int u = H.top().second;
LLI d = -H.top().first;
H.pop();
if (d > dist[u]) continue;
for (i = 0; i < adjList[u].size(); i++) {
int v = adjList[u][i].first;
if ((dist[v] == -1) || (dist[u]+adjList[u][i].second < dist[v])) {
dist[v] = dist[u]+adjList[u][i].second;
H.push(mp(-dist[v],v));
}
}
}
printf("%lld\n",dist[1]);
return 0;
}
