export {};

const N: number = Number(require("fs").readFileSync(0).toString().trim());

let queen: number[] = new Array(N).fill(-1);
let count: number = 0;

const isSafe = (depth: number): boolean => {
    for (let col=0; col<depth; col++) {
        if (queen[col] === queen[depth]) return false;
        else if (Math.abs(depth - col) === Math.abs(queen[depth] - queen[col])) return false;
    }
    return true;
}

const backTracking = (depth: number) => {
    if (depth === N) {
        count++;
        return;
    }

    for (let n=0; n<N; n++) {
        queen[depth] = n;

        if (isSafe(depth)) backTracking(depth+1);
    }
}

backTracking(0);
console.log(count);