let main = (input) => {
    let id = parseInt(input)
    let output = ""
    for (let result = id; result != 0; result = Math.floor(result / 26)) {
        let which = result % 26
        if (which == 0) {
            which = 26
            result = result - 26
        }
        output = String.fromCharCode(97 + which - 1) + output
    }

    console.log(output)
}

main(require('fs').readFileSync('/dev/stdin', 'utf8'))