const input = require("fs").readFileSync("/dev/stdin", "utf8")
;(input => {

    let N = input - 0
    const char = ['a', 'a' ,'a' , 'a','a']

    let n = ''
    while (N !== 0) {
        const c = N % 26 || 26
        n = String.fromCharCode(c + 96) + n
        N -= c
        N /= 26
    }

    console.log(n)

})(input)

