import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);

		long N = scan.nextLong();
		StringBuilder sb = new StringBuilder();

		while(true) {
			N--;
			sb.append((char)('a' + (N % 26)));
			if(N < 26) {
				break;
			}
			N /= 26;
		}

		System.out.println(sb.reverse().toString());

	}
} import java.util.Scanner; Scanner java.util public class Main {
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);

		long N = scan.nextLong();
		StringBuilder sb = new StringBuilder();

		while(true) {
			N--;
			sb.append((char)('a' + (N % 26)));
			if(N < 26) {
				break;
			}
			N /= 26;
		}

		System.out.println(sb.reverse().toString());

	}
} Main public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);

		long N = scan.nextLong();
		StringBuilder sb = new StringBuilder();

		while(true) {
			N--;
			sb.append((char)('a' + (N % 26)));
			if(N < 26) {
				break;
			}
			N /= 26;
		}

		System.out.println(sb.reverse().toString());

	} main {
		Scanner scan = new Scanner(System.in);

		long N = scan.nextLong();
		StringBuilder sb = new StringBuilder();

		while(true) {
			N--;
			sb.append((char)('a' + (N % 26)));
			if(N < 26) {
				break;
			}
			N /= 26;
		}

		System.out.println(sb.reverse().toString());

	} Scanner scan = new Scanner(System.in); scan new Scanner(System.in) long N = scan.nextLong(); N scan.nextLong() scan.nextLong scan StringBuilder sb = new StringBuilder(); sb new StringBuilder() while(true) {
			N--;
			sb.append((char)('a' + (N % 26)));
			if(N < 26) {
				break;
			}
			N /= 26;
		} true {
			N--;
			sb.append((char)('a' + (N % 26)));
			if(N < 26) {
				break;
			}
			N /= 26;
		} N-- N sb.append((char)('a' + (N % 26))) sb.append sb (char)('a' + (N % 26)) 'a' (N % 26) N 26 if(N < 26) {
				break;
			} N < 26 N 26 {
				break;
			} break; N /= 26 N 26 System.out.println(sb.reverse().toString()) System.out.println System.out System System.out sb.reverse().toString() sb.reverse().toString sb.reverse() sb.reverse sb String[] args args public class Main {
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);

		long N = scan.nextLong();
		StringBuilder sb = new StringBuilder();

		while(true) {
			N--;
			sb.append((char)('a' + (N % 26)));
			if(N < 26) {
				break;
			}
			N /= 26;
		}

		System.out.println(sb.reverse().toString());

	}
} public class Main {
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);

		long N = scan.nextLong();
		StringBuilder sb = new StringBuilder();

		while(true) {
			N--;
			sb.append((char)('a' + (N % 26)));
			if(N < 26) {
				break;
			}
			N /= 26;
		}

		System.out.println(sb.reverse().toString());

	}
} Main
import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);

		long N = scan.nextLong();
		StringBuilder sb = new StringBuilder();

		while(true) {
			N--;
			sb.append((char)('a' + (N % 26)));
			if(N < 26) {
				break;
			}
			N /= 26;
		}

		System.out.println(sb.reverse().toString());

	}
}