#include <iostream>
using namespace std;

const int N = 220;
int p[N];
int n,x,y;
int ox[] = {1,-1};
int count;

int dst[N];

bool dfs(int x,int y){
    
    
    if(x==y){
		return true;
    }
    count++;
    dst[x]==1;
    
    for(int i=0;i<2;i++){
        int nx = x+(ox[i]*p[x]);
        if(nx>=1&&nx<=y&&nx!=x&&!dst[nx]){
            if(dfs(nx,y)){
            	return true;
			}
			count--;
			dst[nx] = 0;
        }
    }
    return false;
    
    
}


int main(){
    cin>>n>>x>>y;
    for(int i=1;i<=n;i++) cin>>p[i];
    bool bl = dfs(x,y);
    if(bl){
    	cout << count << endl;
	}else {
		cout << -1 << endl;
	}

    return 0;
}

四个MLE，剩下都AC，姥姥救救