function main(input) {
  	const total = parseInt(input.split('\n')[0], 10)
    let num = 0
	
	for(let a = 1; a < total; a++) {
		for(let b = 1; b < total; b++) {
          	if(a*b > total-1) break
            num++
	  	}
	}

	console.log(num)
}

main(require("fs").readFileSync("/dev/stdin", "utf8"));
