let input = require('fs').readFileSync('/dev/stdin', 'utf8')
// let input = require('fs').readFileSync('./sample_c.txt', 'utf8')
.split(/\n| /)
.slice(0 ,-1)
.map(item => parseInt(item))


const [N] = input



let count = 0



for(let A=1; A*A<N; A++){
    for(let B=A; A*B < N; B++){
        if(A===B)count += 1
        else count += 2
    }
}
console.log(count)