let lines = [];
let reader = require('readline').createInterface({
    input: process.stdin,
    output: process.stdout
});

// 標準入力の読み込み
reader.on('line', function(line) {
    lines.push(line);
});

reader.on('close', function() {
    // 処理の記述
    const n = lines[0];

    let cnt = 0;
    for (let a = 1; a < n; a++) {
        for (let b = a; b < n; b++) {
            if (a * b < n) {
                cnt++;
                if (a != b) {
                    cnt++;
                }
            }
        }
    }


    // 表示
    console.log(cnt);
});