#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define pii pair<int, int>
#define pb push_back
#define ff first
#define ss second
vector<pii> q[200100];
pii d[200100];
map<int, int> dd[200100];
map<int, vector<pii>> dq[200100];
map<int, ll> dp[200100];
map<int, int> us[200100];
void solve(){
int n, m;
cin>>n>>m;
for(int i=1; i<=m; i++){
int l, r, x, c;
cin>>l>>r>>x>>c;
q[l].pb({r, i});
q[r].pb({l, i});
d[i] = {x, c};
}
for(int i=1; i<=n; i++){
for(pii h: q[i]){
int to = h.ff;
int e = h.ss;
dd[i][d[e].ff] += d[e].ss;
dq[i][d[e].ff].pb(h);
}
}
set<pair<ll, pii>> s;
s.insert({0, {1, 0}});
while(s.size()){
auto it = s.begin();
int v = it -> ss.ff, k = it -> ss.ss;
if(us[v][k]){
s.erase(s.begin());
continue;
}
us[v][k] = 1;
dp[v][k] = it -> ff;
//cout<<v<<' '<<k<<' '<<dp[v][k]<<'\n';
s.erase(it);
if(k == 0 or us[v][0] == 0){
us[v][0] = 1;
dp[v][0] = dp[v][k];
for(pii h: q[v]){
int to = h.ff;
int c = d[h.ss].ff;
int g = d[h.ss].ss;
s.insert({dp[v][k] + dd[v][c] - g, {to, 0}});
s.insert({dp[v][k] + dd[to][c], {to, c}});
}
}
else{
for(pii h: dq[v][k]){
int to = h.ff;
int c = d[h.ss].ff;
int g = d[h.ss].ss;
s.insert({dp[v][k] - g, {to, 0}});
s.insert({dp[v][k] - g + dd[to][c], {to, c}});
}
}
}
ll ans = 1e18;
for(int i=0; i<=m; i++){
if(us[n][i]) ans = min(ans, dp[n][i]);
}
if(ans == 1e18) cout<<-1;
else cout<<ans;
}
signed main(){
solve();
}
