var
  n,a,b,i,j,k:integer;
  c,d,e:array[1..200] of integer;
begin
  assign(input,'lift.in');
  reset(input);
  readln(n,a,b);
  for i:=1 to n do read(c[i]);
  close(input);
  for i:=1 to n do d[i]:=201;
  e[1]:=a;
  d[a]:=0;
  i:=1;j:=2;
  repeat
    k:=e[i]+c[e[i]];
    if (k<=n)and(d[k]>d[e[i]]+1) then begin e[j]:=k;j:=j+1;d[k]:=d[e[i]]+1;end;
    k:=e[i]-c[e[i]];
    if (k>0)and(d[k]>d[e[i]]+1) then begin e[j]:=k;j:=j+1;d[k]:=d[e[i]]+1;end;
    i:=i+1;
  until (i=j)or(d[b]<201);
  assign(output,'lift.out');
  rewrite(output);
  if d[b]<201 then writeln(d[b]) else writeln(-1);
  close(output);
end.