const rl = require("readline").createInterface({ input: process.stdin });
var iter = rl[Symbol.asyncIterator]();
const readline = async () => (await iter.next()).value;

void async function () {
    // Write your code here
   let arr = [];
    for(let i = 0 ; i < 10 ; i++){
        const total = parseInt(await readline()); 
        if(total) {
            let sum = total;
            let res = 0;
            while(sum >=3) {
                const rest = sum % 3;
                res += Math.floor(sum / 3);
                 sum = Math.floor( sum / 3) + rest;
            }
            if(sum >= 2) res++;

            console.log(res)
        }else {
            break;
        }
    }
}()