function ans(n) {
    for (let i = 1; i <= 14000; i++) {
        if (i % 7 == 0) n += 6;
        n--;
        if (n == 0) return i;
    }
}
function Main(input) {
    const n = parseInt(input.replace("\n", ""));
    console.log(ans(n));
}
Main(require("fs").readFileSync("/dev/stdin", "utf8"));