function Main2(input){
    let arr =[];
    const num = Number(input);
    const arphabet = 'abcdefghijklmnopqrstuvwxyz'.split('');
    const allen = arphabet.length;
    if(1 <= num && num <= 26){
        return console.log(arphabet[num-1]);
    } else if(num <= (26*26 + 26)){
        const num_2 = num - 26 -1;
        const digit_1 = num_2 % allen;
        const digit_2 = Math.floor(num_2 / allen) % allen;
        return console.log(arphabet[digit_2] + arphabet[digit_1]);
    } else if(num <= (26*26*26 + (26*26 + 26))){
        const num_2 = num - (26*26 + 26) -1;
        const digit_1 = num_2 % allen;
        const digit_2 = Math.floor(num_2 / allen) % allen;
        const digit_3 = Math.floor(digit_2 / allen) % allen;
        return console.log(arphabet[digit_3] +arphabet[digit_2] + arphabet[digit_1]);
    } else if(num <= (26*26*26*26 + (26*26*26 + 26))){
        const num_2 = num - (26*26*26 + 26) -1;
        const digit_1 = num_2 % allen;
        const digit_2 = Math.floor(num_2 / allen) % allen;
        const digit_3 = Math.floor(digit_2 / allen) % allen;
        const digit_4 = Math.floor(digit_3 / allen) % allen;
        return console.log(arphabet[digit_4] + arphabet[digit_3] +arphabet[digit_2] + arphabet[digit_1]);
    } else if(num <= (26*26*26*26*26 + (26*26*26*26 + 26))){
        const num_2 = num - (26*26*26*26 + 26) -1;
        const digit_1 = num_2 % allen;
        const digit_2 = Math.floor(num_2 / allen) % allen;
        const digit_3 = Math.floor(digit_2 / allen) % allen;
        const digit_4 = Math.floor(digit_3 / allen) % allen;
        const digit_5 = Math.floor(digit_4 / allen) % allen;
        return console.log(arphabet[digit_5] + arphabet[digit_4] + arphabet[digit_3] +arphabet[digit_2] + arphabet[digit_1]);
    }
}
Main(require("fs").readFileSync("/dev/stdin", "utf8"));
