// Enter your code here 

let NumberOdCandles = Int(readLine()!)!

let candlesHeightArray = readLine()!.characters.split(" ").map{Int(String($0))!}

var count = 0
for row in 0...candlesHeightArray.count-3
{
    if row == 0
    {
        if candlesHeightArray[row] > candlesHeightArray[row+1]
        {
            count = count + 1
        }
        else if candlesHeightArray[row+1] > candlesHeightArray[row+2]
        {
            count = count + 1
        }
    }
    else
    {
         if candlesHeightArray[row+1] > candlesHeightArray[row] && candlesHeightArray[row+1] >     candlesHeightArray[row+2]
        {
            count = count + 1
        }
        else if row == candlesHeightArray.count-3 && candlesHeightArray[row+1] > candlesHeightArray[row]
        {
            count = count + 1
        }
        else if row == candlesHeightArray.count-3 && candlesHeightArray[row+2] > candlesHeightArray[row+1]
        {
            count = count + 1
        }
    }
}
print(count)