const fs = require('fs')
const chars = 'abcdefghijklmnopqrstuvwxyz'
 
function changeBase(value) {
    let result = ''
    while (value > 0) {
      	const remand = value % 26
    	const c = chars[(remand + 25) % 26]
        result = c + result
        if (remand === 0) {
        	value = Math.floor(value / 26) - 1
        } else {
        	value = Math.floor(value / 26)
        }
    }
	return result
}
 
const inputValue = parseInt(fs.readFileSync('/dev/stdin', 'utf8'))
console.log(changeBase(inputValue))