C++ :

#include <iostream>

#include <cstdio>
#include <cstring>
#include <cmath>
using namespace std;
int n,a,b,t;
int ans=0x7f;
int edge[205][205];
int f[209][209];

int main()
{
	cin>>n>>a>>b;
	memset(edge,0x7f/2,sizeof(edge));
	memset(f,0x7f/2,sizeof(f));
	for (int i=1; i<=n; i=i+1) 
	{
		f[i][i]=0;
	 	cin>>t;
	 	if (i+t<=n)
		{
			edge[i][i+t]=1;
	 		f[i][i+t]=edge[i][i+t];
	 	}
		if (i-t>=1)
		{
			edge[i][i-t]=1;
	 		f[i][i-t]=edge[i][i-t];
	 	}
	}
	for (int k=1; k<=n; k++)
	  for (int i=1; i<=n; i++)
	    if (i!=k)
	      for (int j=1; j<=n; j=j+1)
	        if (i!=j&&j!=k)
	        {
	        	f[i][j]=min(f[i][j],f[i][k]+f[k][j]);
			}
	if (f[a][b]!=f[0][0]) cout<<f[a][b]<<endl;
	else cout<<-1<<endl;
}

Pascal :

program gallane_Lift;
var n,i,j,l,a,b,p:longint;
 lift,step:array[0..200] of longint;
begin
    read(n,a,b);
    for i:=1 to n do read(lift[i]);
    for i:=1 to n do step[i]:=-1;
 step[a]:=0;
    p:=0; l:=1;
    while (l>0) and (step[b]=-1) do
    begin
        l:=0;
        for i:=1 to n do
        if step[i]=p then
        begin
         j:=i-lift[i];
            if (j>0) and (step[j]=-1) then
            begin
                step[j]:=p+1;
                l:=l+1;
            end;
            j:=i+lift[i];
            if (j<=n) and (step[j]=-1) then
            begin
                step[j]:=p+1;
                l:=l+1;
            end;
        end;
     p:=p+1;
    end;
 write(step[b]);
end.