import sequtils, strutils
 
let
  n = stdin.readLine
  ab = stdin.readLine.split.map parseInt
  ps = stdin.readLine.split
var
  a = ab[0]
  b = ab[1]
 
for i, v in ps:
  if v == "1":
    dec a
  elif v == "2":
    dec b
  else:
    dec a
    dec b
  if a < 0 or b < 0:
    echo i.succ
    quit()
 
echo -1