# include <algorithm>
# include <iostream>
# include <iomanip>
# include <string>
# include <cmath>
# include <deque>
# include <stack>
# include <stdio.h>
# include <set>
# include <map>
# include <queue>
using namespace std;

const long long INF=1e18;
set< pair< long long ,long long > > q;

int main()
{
	long long m,n,s,f,x,y,t,dis,i,d[200],to,v;
	cin>>n>>s>>f>>m;

	vector< pair< pair< long long , long long >, long long > > a[n+1];

	for(i=1;i<=m;i++)
	{
		cin>>x>>t>>y>>dis;
		a[x].push_back(make_pair(make_pair(y,t),dis));
	}

	for(i=1;i<=n;i++)
	   d[i]=INF;
    d[s]=0;

    q.insert(make_pair(s,0));

    while(!q.empty())
    {
    	v=q.begin()->first;
    	t=q.begin()->second;
    	q.erase(q.begin());

    	for(i=0;i<a[v].size();i++)
    	{
    		to=a[v][i].first.first;
    		x=a[v][i].first.second;
            y=a[v][i].second;

    		if(d[to]>=(abs(x-t)+abs(y-x)+d[v]) && x>=t)
    		{
    			 q.erase(make_pair(to,y));
    			 d[to]=abs(x-t)+abs(y-x)+d[v];
    			 q.insert(make_pair(to,y));
    		}
    	}
    }

    if(d[f]>=INF)
      cout<<"-1"<<endl;
    else cout<<d[f]<<endl;

	return 0;
}
/*
5
1 2
7
1 2 3 8
1 0 2 100
1 0 5 9
3 8 4 10
3 8 5 10
5 10 4 13
4 10 2 12
*/