let input = [
    5,
    -4
];
let print = this.print || console.log;
let gets = this.gets || ((arr, index) => () => arr[index++])(input, 0);


let n = Number(gets());
let x = Number(gets());
let result = 1;
let ifac = 1;

for (let i = 1; i <= n; i++){
    ifac *= i;

    result += ifac / Math.pow(x, i);
}
print(result.toFixed(5));