function Main(arg) {
    let n = BigInt(arg.trim());
    let result = '';
    while(n > 26) {

      let surplus = n % 26n;
      if (surplus == 0){
        result = 'z' + result;
        n = n-1n;
      } else {
        result = String.fromCharCode(Number(surplus) + 96)  + result;
      }
      n = n / 26n;
    }
    if(n != 0) {
      result = String.fromCharCode(Number(n) + 96)  + result;
    } else {
      result = 'z' + result;
    }
    console.log(result);
}
Main(require("fs").readFileSync("/dev/stdin", "utf8"));
