#include <iostream>
using namespace std;

int n, a, b;
int k[210];
bool flag[210];
int ans = 1e9;

void dfs(int num, int step)
{
    if (step > ans) return;
    if (num == b)
    {
        ans = min(step, ans);
        return;
    }
    flag[num] = true;
    if(num + k[num] <= n && !flag[num+k[num]])
    {
        dfs(num + k[num], step + 1);
    }
    if(num - k[num] >= 1 && !flag[num-k[num]])
    {
        dfs(num - k[num], step + 1);
    }
    flag[num] = false;
}

int main()
{
    cin >> n >> a >> b;
    for (int i = 1; i <= n; i++) cin >> k[i];
    dfs(a, 0);
    if (ans != 1e9) cout << ans << endl;
    else cout << -1 << endl;
    return 0;
}