fac

let input = ['3',
'2'
];
let print = this.print || console.log;
let gets = this.gets || ((arr, index) => () => arr[index++])(input, 0);

var N = +gets();
var X = +gets();
var sum = 1;
var y = 1;


for(var i = 1; i <= N; i++){
    y *= i;
    sum += y/Math.pow(X,i);

}

print(sum.toFixed(5))