"use strict"
const create = () => {
    const input = require("fs").readFileSync("/dev/stdin", "utf8").trim().split("\n");
    const res = {
        "list": input, "index": 0, "max": input.length,
        "hasNext": function() {return this.index < this.max},
        "next": function() { if (!this.hasNext()) {throw "ArrayIndexOutOfBoundsException";}else{return this.list[this.index++];}}
    };
    return res;
}
const o = create();
const next = () => o.next()
const nextInt = () => parseInt(o.next())
const nextStrArray = () => o.next().split(" ")
const nextIntArray = () => o.next().split(" ").map(el => parseInt(el))
const nextCharArray = () => o.next().split("")
const hasNext = () => o.hasNext()
const myout = (...x) => console.log(...x)
const Main = () => {
    let n = BigInt(next())
    let ans = []
    let alpha = "abcdefghijklmnopqrstuvwxyz"
    let div = 26n
    let cnt = 0
    while(cnt < 10 && n > 0n){
        let rem = n % div
        while(rem > 26n){
            rem /= 26n
        }
      	if(rem == 1n) rem = 0n
        ans.push(alpha[Number(rem)])
        n -= div
	    div *= 26n
        cnt++
    }
    console.log(ans.reverse().join(""))
}
Main()
