"use strict";
    
const main = arg => {
    arg = arg.trim().split("\n");
    const N = parseInt(arg[0]);
    
    let answer;
    
    if(N <= 6) {
        answer = 1;
    } else if(N <= 11) {
        answer = 2;
    } else {
        let temp = N % 11;
        answer = Math.floor(N / 11) + Math.ceil(temp / 6);
    }

    console.log(answer);
}
main(require('fs').readFileSync('/dev/stdin', 'utf8'));