#include<queue>
#include<math.h>
#include<stdio.h>
#include<iostream>
#include<vector>
#include<iomanip>
#include<string.h>
#include<algorithm>
#include<cmath>
#include<cstdio>
#include<cstring>
#include<stack>
#include<climits>
#include<fstream>
#include<string>
using namespace std;
#define LL long long
const int N = 1e5 + 10;
const int INF = 0x3f3f3f3f;
struct Edge 
{
    int to , time;
    Edge (int t , int tm ) : to(t) , time(tm) {}
};
struct Node
{
    int id , time;
    Node( int i , int t ) : id(i) , time(t) {}
    bool operator>( const Node& other ) const
    {
        return time > other.time;
    }
};
vector<int> b , c;
vector<vector<Edge>> adj;
int getWaitTime( int u , int currentTime )
{
    int cycle = b[u] + c[u];
    int mod = currentTime % cycle;
    if ( mod < c[u] )
    {
        return 0;
    }
    return cycle - mod;
}
int dijkstra( int n )
{
    vector<int> dist( n + 1 , INT_MAX );
    priority_queue<Node , vector<Node> , greater<Node>> pq;
    dist[0] = 0;
    pq.push( Node( 0 , 0 ) );  
    while ( !pq.empty() )
    {
        Node node = pq.top();
        pq.pop();       
        if ( node.id == n )
        {
            return node.time;
        }
        if ( node.time > dist[node.id] )
        {
            continue;
        }    
        for ( Edge& edge : adj[node.id] )
        {
            int next = edge.to;
            int arrival = node.time + edge.time;  
            if ( next != n )
            {
                int wait = getWaitTime( next , arrival );
                arrival += wait;
            }            
            if ( arrival < dist[next] )
            {
                dist[next] = arrival;
                pq.push( Node( next , arrival ) );
            }
        }
    }
    return -1;
}
int main()
{
    ios::sync_with_stdio(false);
    cin.tie(nullptr);    
    int n;
    cin >> n;
    b.resize(n);
    c.resize(n);
    adj.resize( n + 1 ); 
    for ( int i = 0 ; i < n ; ++i )
    {
        cin >> b[i] >> c[i];
    }   
    int m;
    cin >> m;
    for ( int i = 0 ; i < m ; ++i )
    {
        int x , y , t;
        cin >> x >> y >> t;
        adj[x].emplace_back( y , t );
        adj[y].emplace_back( x , t );
    }   
    cout << dijkstra(n) << endl;
    return 0;
}