import strutils

proc countIncreases(): uint =
  var
    line = ""
    prevDepth = high(uint)
  while readLine(stdin, line):
    if line.len() > 0:
      let depth = parseUint(line)
      if depth > prevDepth:
        result.inc()
      prevDepth = depth

proc main(): int =
  try:
    echo countIncreases()
  except ValueError:
    result = -1

when isMainModule:
  quit(main())