function factorial(n){
        if(n < 0){
            return -1;
        }
        if(n == 0 || n == 1){
            return 1;
        }else{
            return n * factorial(n-1);
        }
    }
    let value = input.split(/[\n]/g);
    let x = parseFloat(value[0]);
    let y = parseFloat(value[1]);
    let ans = (Math.pow(x,y) * Math.exp(-x))/factorial(y);
    console.log(ans.toFixed(3));