'use strict'

function Main(input) {
    const N = parseInt(input.trim())
    const faces = [7, 5, 3]
    const base = faces.length
    const combos = new Array(N.toString().length - base + 1)
        .fill(0)
        .map((x, i) => getCombos(base, base + i))
        .reduce((acc, val) => acc.concat(val), [])
        .filter(combo => {
            //console.log(combo)
            const condA = parseInt(combo.map(x => faces[x]).join('')) <= N
            const condB = new Array(base)
                .fill(0)
                .every((x, i) => combo.indexOf(i) !== -1)
            return condA && condB
        })
    const output = combos.length
    console.log(output)
}

function getCombos(base, length) {
    const combos = [new Array(length).fill(0)]
    const num = Math.pow(base, length)
    for (let i = 1; i < num; i++) {
        const c = Array.from(combos[i - 1])
        increment(c, base)
        combos.push(c)
    }
    return combos
}

function increment(combo, base) {
    combo[0] += 1
    for (let i = 0; i < combo.length - 1; i++) {
        if (combo[i] === base) {
            combo[i] = 0
            combo[i + 1] += 1
        }
    }
}

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