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

	console.log(num)
}

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