#include <vector>
#include <fstream>
#include <iostream>
#include <cmath>
#include <stdio.h>
#define inf 100000000000
using namespace std;
ifstream in("input.txt", ios::in);
ofstream out("output.txt", ios::out);
int n, m;
long long* w;
long long** graph;
void gograph();
void dijkstra(long long** graph);
int main()
{
    gograph();
    dijkstra(graph);
    return 0;
}
void gograph()
{
    in >> n;
    w = new long long[n];
    for (int i = 0; i<n; i++)
        in >> w[i];
    w[n-1] = 0;
    graph = new long long*[n];
    for (int i = 0; i<n; i++)
        graph[i] = new long long[n];
    for (int i = 0; i<n; i++)
        for (int j = 0; j<n; j++)
            graph[i][j] = -1;
    in >> m;
    for (int i = 0; i<m; i++)
    {
        long long x, y;
        in >> x >> y;
        x--;y--;
        graph[x][y] = w[x];
        graph[y][x] = w[y];
    }

}
void dijkstra(long long** graph)
{
    if (n == 1)
    {
        out << 0;
        return;
    }
    int to;
    long long len;
    bool* used = new bool[n];
    long long* d = new long long[n];
    long long* p = new long long[n];
    for (int i = 0; i<n; i++)
    {
        used[i] = false;
        d[i] = inf;
    }
    d[0] = 0;
    for (int i = 0; i<n; i++)
    {
        long long v = -1;
        for (int j = 0; j<n; j++)
            if (!used[j] && (v == -1 || d[j] < d[i]))
                v = j;
        if (d[v] == inf)
            break;
        used[v] = true;
        for (int j = 0; j<n; j++)
        {
            if (graph[v][j]>=0)
            {
                to = j;
                len = graph[v][j];
                if (d[v] + len < d[to])
                {
                    d[to] = d[v] + len;
                    p[to] = v;
                }
            }
        }
    }
    out << (d[n-1] != inf ? d[n-1] : -1);
}