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