"use strict";
    
const main = arg => {
    arg = arg.trim().split("\n");
    const N = parseInt(arg[0].split(" ")[0]);
    let answer = 0;

    for(let i=1; i<N; i++) {
        if(N % i === 0) {
            answer += (N / i) - 1;
        } else {
            answer += Math.floor(N / i);
        }
    }
    
    console.log(answer);
}
main(require('fs').readFileSync('/dev/stdin', 'utf8'));