import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long n = sc.nextLong() - 1;
        long base = 26;
        int idx = 0;
        long[] counts = new long[10];
        for (int i = 0; i < 11; i++) {
            if (n - base < 0) {
                idx = i;
                break;
            }
            n -= base;
            base *= 26;
        }
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i <= idx; i++) {
            sb.append((char)(n % 26 + 'a'));
            n /= 26;
        }
        System.out.println(sb.reverse());
    }
} import java.util.*; util.* java public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long n = sc.nextLong() - 1;
        long base = 26;
        int idx = 0;
        long[] counts = new long[10];
        for (int i = 0; i < 11; i++) {
            if (n - base < 0) {
                idx = i;
                break;
            }
            n -= base;
            base *= 26;
        }
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i <= idx; i++) {
            sb.append((char)(n % 26 + 'a'));
            n /= 26;
        }
        System.out.println(sb.reverse());
    }
} Main public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long n = sc.nextLong() - 1;
        long base = 26;
        int idx = 0;
        long[] counts = new long[10];
        for (int i = 0; i < 11; i++) {
            if (n - base < 0) {
                idx = i;
                break;
            }
            n -= base;
            base *= 26;
        }
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i <= idx; i++) {
            sb.append((char)(n % 26 + 'a'));
            n /= 26;
        }
        System.out.println(sb.reverse());
    } main {
        Scanner sc = new Scanner(System.in);
        long n = sc.nextLong() - 1;
        long base = 26;
        int idx = 0;
        long[] counts = new long[10];
        for (int i = 0; i < 11; i++) {
            if (n - base < 0) {
                idx = i;
                break;
            }
            n -= base;
            base *= 26;
        }
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i <= idx; i++) {
            sb.append((char)(n % 26 + 'a'));
            n /= 26;
        }
        System.out.println(sb.reverse());
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) long n = sc.nextLong() - 1; n sc.nextLong() - 1 sc.nextLong() sc.nextLong sc 1 long base = 26; base 26 int idx = 0; idx 0 long[] counts = new long[10]; counts new long[10] 10 for (int i = 0; i < 11; i++) {
            if (n - base < 0) {
                idx = i;
                break;
            }
            n -= base;
            base *= 26;
        } int i = 0; int i = 0; i 0 i < 11 i 11 i++ i++ i {
            if (n - base < 0) {
                idx = i;
                break;
            }
            n -= base;
            base *= 26;
        } {
            if (n - base < 0) {
                idx = i;
                break;
            }
            n -= base;
            base *= 26;
        } if (n - base < 0) {
                idx = i;
                break;
            } n - base < 0 n - base n base 0 {
                idx = i;
                break;
            } idx = i idx i break; n -= base n base base *= 26 base 26 StringBuilder sb = new StringBuilder(); sb new StringBuilder() for (int i = 0; i <= idx; i++) {
            sb.append((char)(n % 26 + 'a'));
            n /= 26;
        } int i = 0; int i = 0; i 0 i <= idx i idx i++ i++ i {
            sb.append((char)(n % 26 + 'a'));
            n /= 26;
        } {
            sb.append((char)(n % 26 + 'a'));
            n /= 26;
        } sb.append((char)(n % 26 + 'a')) sb.append sb (char)(n % 26 + 'a') n % 26 n 26 'a' n /= 26 n 26 System.out.println(sb.reverse()) System.out.println System.out System System.out sb.reverse() sb.reverse sb String[] args args public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long n = sc.nextLong() - 1;
        long base = 26;
        int idx = 0;
        long[] counts = new long[10];
        for (int i = 0; i < 11; i++) {
            if (n - base < 0) {
                idx = i;
                break;
            }
            n -= base;
            base *= 26;
        }
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i <= idx; i++) {
            sb.append((char)(n % 26 + 'a'));
            n /= 26;
        }
        System.out.println(sb.reverse());
    }
} public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long n = sc.nextLong() - 1;
        long base = 26;
        int idx = 0;
        long[] counts = new long[10];
        for (int i = 0; i < 11; i++) {
            if (n - base < 0) {
                idx = i;
                break;
            }
            n -= base;
            base *= 26;
        }
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i <= idx; i++) {
            sb.append((char)(n % 26 + 'a'));
            n /= 26;
        }
        System.out.println(sb.reverse());
    }
} Main
import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long n = sc.nextLong() - 1;
        long base = 26;
        int idx = 0;
        long[] counts = new long[10];
        for (int i = 0; i < 11; i++) {
            if (n - base < 0) {
                idx = i;
                break;
            }
            n -= base;
            base *= 26;
        }
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i <= idx; i++) {
            sb.append((char)(n % 26 + 'a'));
            n /= 26;
        }
        System.out.println(sb.reverse());
    }
}