import java.util.*;

public class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    long n = sc.nextLong();
    int k = 0;
    long t = 0;
    long tt = 26;
    while(t < n) {
      t += tt;
      tt *= 26;
      k++;
    }
    String[] s = {"a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m", "n", "o", "p", "q", "r", "s", "t", "u", "v", "w", "x", "y", "z"};
    long r = n;
    for(int i = 1; i < k; i++) {
      r -= (long)Math.pow(26, i);
    }
    String ans = "";
    for(int i = 1; i <= k; i++) {
      int rr = (int)(r % 26);
      if((rr % 26) == 0) {
        ans = s[25] + ans;
        r = (r / 26);
      } else {
        ans = s[rr - 1] + ans;
        r = (r / 26) + 1;
      }
    }
    System.out.println(ans);
  }
} import java.util.*; util.* java public class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    long n = sc.nextLong();
    int k = 0;
    long t = 0;
    long tt = 26;
    while(t < n) {
      t += tt;
      tt *= 26;
      k++;
    }
    String[] s = {"a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m", "n", "o", "p", "q", "r", "s", "t", "u", "v", "w", "x", "y", "z"};
    long r = n;
    for(int i = 1; i < k; i++) {
      r -= (long)Math.pow(26, i);
    }
    String ans = "";
    for(int i = 1; i <= k; i++) {
      int rr = (int)(r % 26);
      if((rr % 26) == 0) {
        ans = s[25] + ans;
        r = (r / 26);
      } else {
        ans = s[rr - 1] + ans;
        r = (r / 26) + 1;
      }
    }
    System.out.println(ans);
  }
} Main public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    long n = sc.nextLong();
    int k = 0;
    long t = 0;
    long tt = 26;
    while(t < n) {
      t += tt;
      tt *= 26;
      k++;
    }
    String[] s = {"a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m", "n", "o", "p", "q", "r", "s", "t", "u", "v", "w", "x", "y", "z"};
    long r = n;
    for(int i = 1; i < k; i++) {
      r -= (long)Math.pow(26, i);
    }
    String ans = "";
    for(int i = 1; i <= k; i++) {
      int rr = (int)(r % 26);
      if((rr % 26) == 0) {
        ans = s[25] + ans;
        r = (r / 26);
      } else {
        ans = s[rr - 1] + ans;
        r = (r / 26) + 1;
      }
    }
    System.out.println(ans);
  } main {
    Scanner sc = new Scanner(System.in);
    long n = sc.nextLong();
    int k = 0;
    long t = 0;
    long tt = 26;
    while(t < n) {
      t += tt;
      tt *= 26;
      k++;
    }
    String[] s = {"a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m", "n", "o", "p", "q", "r", "s", "t", "u", "v", "w", "x", "y", "z"};
    long r = n;
    for(int i = 1; i < k; i++) {
      r -= (long)Math.pow(26, i);
    }
    String ans = "";
    for(int i = 1; i <= k; i++) {
      int rr = (int)(r % 26);
      if((rr % 26) == 0) {
        ans = s[25] + ans;
        r = (r / 26);
      } else {
        ans = s[rr - 1] + ans;
        r = (r / 26) + 1;
      }
    }
    System.out.println(ans);
  } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) long n = sc.nextLong(); n sc.nextLong() sc.nextLong sc int k = 0; k 0 long t = 0; t 0 long tt = 26; tt 26 while(t < n) {
      t += tt;
      tt *= 26;
      k++;
    } t < n t n {
      t += tt;
      tt *= 26;
      k++;
    } t += tt t tt tt *= 26 tt 26 k++ k String[] s = {"a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m", "n", "o", "p", "q", "r", "s", "t", "u", "v", "w", "x", "y", "z"}; s {"a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m", "n", "o", "p", "q", "r", "s", "t", "u", "v", "w", "x", "y", "z"} "a" "b" "c" "d" "e" "f" "g" "h" "i" "j" "k" "l" "m" "n" "o" "p" "q" "r" "s" "t" "u" "v" "w" "x" "y" "z" long r = n; r n for(int i = 1; i < k; i++) {
      r -= (long)Math.pow(26, i);
    } int i = 1; int i = 1; i 1 i < k i k i++ i++ i {
      r -= (long)Math.pow(26, i);
    } {
      r -= (long)Math.pow(26, i);
    } r -= (long)Math.pow(26, i) r (long)Math.pow(26, i) Math.pow Math 26 i String ans = ""; ans "" for(int i = 1; i <= k; i++) {
      int rr = (int)(r % 26);
      if((rr % 26) == 0) {
        ans = s[25] + ans;
        r = (r / 26);
      } else {
        ans = s[rr - 1] + ans;
        r = (r / 26) + 1;
      }
    } int i = 1; int i = 1; i 1 i <= k i k i++ i++ i {
      int rr = (int)(r % 26);
      if((rr % 26) == 0) {
        ans = s[25] + ans;
        r = (r / 26);
      } else {
        ans = s[rr - 1] + ans;
        r = (r / 26) + 1;
      }
    } {
      int rr = (int)(r % 26);
      if((rr % 26) == 0) {
        ans = s[25] + ans;
        r = (r / 26);
      } else {
        ans = s[rr - 1] + ans;
        r = (r / 26) + 1;
      }
    } int rr = (int)(r % 26); rr (int)(r % 26) r 26 if((rr % 26) == 0) {
        ans = s[25] + ans;
        r = (r / 26);
      } else {
        ans = s[rr - 1] + ans;
        r = (r / 26) + 1;
      } (rr % 26) == 0 (rr % 26) rr 26 0 {
        ans = s[25] + ans;
        r = (r / 26);
      } ans = s[25] + ans ans s[25] + ans s[25] s 25 ans r = (r / 26) r (r / 26) r 26 {
        ans = s[rr - 1] + ans;
        r = (r / 26) + 1;
      } ans = s[rr - 1] + ans ans s[rr - 1] + ans s[rr - 1] s rr - 1 rr 1 ans r = (r / 26) + 1 r (r / 26) + 1 (r / 26) r 26 1 System.out.println(ans) System.out.println System.out System System.out ans String[] args args public class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    long n = sc.nextLong();
    int k = 0;
    long t = 0;
    long tt = 26;
    while(t < n) {
      t += tt;
      tt *= 26;
      k++;
    }
    String[] s = {"a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m", "n", "o", "p", "q", "r", "s", "t", "u", "v", "w", "x", "y", "z"};
    long r = n;
    for(int i = 1; i < k; i++) {
      r -= (long)Math.pow(26, i);
    }
    String ans = "";
    for(int i = 1; i <= k; i++) {
      int rr = (int)(r % 26);
      if((rr % 26) == 0) {
        ans = s[25] + ans;
        r = (r / 26);
      } else {
        ans = s[rr - 1] + ans;
        r = (r / 26) + 1;
      }
    }
    System.out.println(ans);
  }
} public class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    long n = sc.nextLong();
    int k = 0;
    long t = 0;
    long tt = 26;
    while(t < n) {
      t += tt;
      tt *= 26;
      k++;
    }
    String[] s = {"a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m", "n", "o", "p", "q", "r", "s", "t", "u", "v", "w", "x", "y", "z"};
    long r = n;
    for(int i = 1; i < k; i++) {
      r -= (long)Math.pow(26, i);
    }
    String ans = "";
    for(int i = 1; i <= k; i++) {
      int rr = (int)(r % 26);
      if((rr % 26) == 0) {
        ans = s[25] + ans;
        r = (r / 26);
      } else {
        ans = s[rr - 1] + ans;
        r = (r / 26) + 1;
      }
    }
    System.out.println(ans);
  }
} Main
import java.util.*;

public class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    long n = sc.nextLong();
    int k = 0;
    long t = 0;
    long tt = 26;
    while(t < n) {
      t += tt;
      tt *= 26;
      k++;
    }
    String[] s = {"a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m", "n", "o", "p", "q", "r", "s", "t", "u", "v", "w", "x", "y", "z"};
    long r = n;
    for(int i = 1; i < k; i++) {
      r -= (long)Math.pow(26, i);
    }
    String ans = "";
    for(int i = 1; i <= k; i++) {
      int rr = (int)(r % 26);
      if((rr % 26) == 0) {
        ans = s[25] + ans;
        r = (r / 26);
      } else {
        ans = s[rr - 1] + ans;
        r = (r / 26) + 1;
      }
    }
    System.out.println(ans);
  }
}