
import java.io.InputStreamReader
import java.io.BufferedReader

//
fun _Do(){
    
    val scanEx = ScannerEx()
    
    //
    val X = scanEx.nextInt()
    val k = scanEx.nextInt()
    //val ia = scanEx.ints()

    println(Math.max(0,X-k))
}

//
fun main( argv : Array<String> ) {
    _Do()
}

//
class ScannerEx {
    fun nextString():String{
        if( idx == 0 || strings.size <= idx)
        {
            idx = 0
            strings = bufferedReader.readLine().split(' ')
        }
        var v = strings[idx]!!
        idx += 1
        return v
    }
    fun nextInt():Int{
        if( idx == 0 || strings.size <= idx )
        {
            idx = 0
            strings = bufferedReader.readLine().split(' ')
        }
        var v = strings[idx]!!.toInt()
        idx += 1
        return v
    }
    fun nextLong():Long{
        if( idx == 0 || strings.size <= idx)
        {
            idx = 0
            strings = bufferedReader.readLine().split(' ')
        }
        var v = strings[idx]!!.toLong()
        idx += 1
        return v
    }
    private var idx:Int = 0 //
    private var strings:List<String?> = emptyList()   //
    fun strings(): Array<String> {
        val strings = bufferedReader.readLine().split(' ')
        return Array(strings.size, { strings[it] })
    }
    fun ints(): Array<Int> {
        val strings = bufferedReader.readLine().split(' ')
        return Array(strings.size, { strings[it].toInt() })
    }
    fun longs(): Array<Long> {
        val strings = bufferedReader.readLine().split(' ')
        return Array(strings.size, { strings[it].toLong() })
    }
    private var bufferedReader = BufferedReader(InputStreamReader(System.`in`))
}
