import java.util.*;

public class Main {
    public static void main(String[] args) throws Exception {
        // Your code here!
        Scanner sc = new Scanner(System.in);
        long n = sc.nextLong();
        
        int count = 0;
        long ts = 1;
        long tssum = 0;
        for (int i = 2; i < 100; i++) {
            if (n <= tssum) {
                break;
            } else {
                ts *= 26;
                tssum += ts;
                count++;
            }
        }
        
        // System.out.println(count);
        
        long tmp2 = 1;
        long tmpsum = 0;
        for (int i = 0; i < count-1; i++) {
            tmp2 *=26;
            tmpsum += tmp2;
        }
        n -= tmpsum;
        n--;
        
        // System.out.println(n);
        
        long twosix = 1;
        for (int i = 0; i < count-1; i++) {
            twosix *= 26;
        }
        
        String str = "";
        for (int i = 0; i < count; i++) {
            long tmp3 = n / twosix;
            // System.out.println(tmp3);
            char c = (char)(tmp3 + 'a');
            str += c;
            // System.out.println(c);
            
            n -= twosix * tmp3;
            twosix /= 26;
            // System.out.println(n);
        }
        
        System.out.println(str);
    }
} import java.util.*; util.* java public class Main {
    public static void main(String[] args) throws Exception {
        // Your code here!
        Scanner sc = new Scanner(System.in);
        long n = sc.nextLong();
        
        int count = 0;
        long ts = 1;
        long tssum = 0;
        for (int i = 2; i < 100; i++) {
            if (n <= tssum) {
                break;
            } else {
                ts *= 26;
                tssum += ts;
                count++;
            }
        }
        
        // System.out.println(count);
        
        long tmp2 = 1;
        long tmpsum = 0;
        for (int i = 0; i < count-1; i++) {
            tmp2 *=26;
            tmpsum += tmp2;
        }
        n -= tmpsum;
        n--;
        
        // System.out.println(n);
        
        long twosix = 1;
        for (int i = 0; i < count-1; i++) {
            twosix *= 26;
        }
        
        String str = "";
        for (int i = 0; i < count; i++) {
            long tmp3 = n / twosix;
            // System.out.println(tmp3);
            char c = (char)(tmp3 + 'a');
            str += c;
            // System.out.println(c);
            
            n -= twosix * tmp3;
            twosix /= 26;
            // System.out.println(n);
        }
        
        System.out.println(str);
    }
} Main public static void main(String[] args) throws Exception {
        // Your code here!
        Scanner sc = new Scanner(System.in);
        long n = sc.nextLong();
        
        int count = 0;
        long ts = 1;
        long tssum = 0;
        for (int i = 2; i < 100; i++) {
            if (n <= tssum) {
                break;
            } else {
                ts *= 26;
                tssum += ts;
                count++;
            }
        }
        
        // System.out.println(count);
        
        long tmp2 = 1;
        long tmpsum = 0;
        for (int i = 0; i < count-1; i++) {
            tmp2 *=26;
            tmpsum += tmp2;
        }
        n -= tmpsum;
        n--;
        
        // System.out.println(n);
        
        long twosix = 1;
        for (int i = 0; i < count-1; i++) {
            twosix *= 26;
        }
        
        String str = "";
        for (int i = 0; i < count; i++) {
            long tmp3 = n / twosix;
            // System.out.println(tmp3);
            char c = (char)(tmp3 + 'a');
            str += c;
            // System.out.println(c);
            
            n -= twosix * tmp3;
            twosix /= 26;
            // System.out.println(n);
        }
        
        System.out.println(str);
    } main {
        // Your code here!
        Scanner sc = new Scanner(System.in);
        long n = sc.nextLong();
        
        int count = 0;
        long ts = 1;
        long tssum = 0;
        for (int i = 2; i < 100; i++) {
            if (n <= tssum) {
                break;
            } else {
                ts *= 26;
                tssum += ts;
                count++;
            }
        }
        
        // System.out.println(count);
        
        long tmp2 = 1;
        long tmpsum = 0;
        for (int i = 0; i < count-1; i++) {
            tmp2 *=26;
            tmpsum += tmp2;
        }
        n -= tmpsum;
        n--;
        
        // System.out.println(n);
        
        long twosix = 1;
        for (int i = 0; i < count-1; i++) {
            twosix *= 26;
        }
        
        String str = "";
        for (int i = 0; i < count; i++) {
            long tmp3 = n / twosix;
            // System.out.println(tmp3);
            char c = (char)(tmp3 + 'a');
            str += c;
            // System.out.println(c);
            
            n -= twosix * tmp3;
            twosix /= 26;
            // System.out.println(n);
        }
        
        System.out.println(str);
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) long n = sc.nextLong(); n sc.nextLong() sc.nextLong sc int count = 0; count 0 long ts = 1; ts 1 long tssum = 0; tssum 0 for (int i = 2; i < 100; i++) {
            if (n <= tssum) {
                break;
            } else {
                ts *= 26;
                tssum += ts;
                count++;
            }
        } int i = 2; int i = 2; i 2 i < 100 i 100 i++ i++ i {
            if (n <= tssum) {
                break;
            } else {
                ts *= 26;
                tssum += ts;
                count++;
            }
        } {
            if (n <= tssum) {
                break;
            } else {
                ts *= 26;
                tssum += ts;
                count++;
            }
        } if (n <= tssum) {
                break;
            } else {
                ts *= 26;
                tssum += ts;
                count++;
            } n <= tssum n tssum {
                break;
            } break; {
                ts *= 26;
                tssum += ts;
                count++;
            } ts *= 26 ts 26 tssum += ts tssum ts count++ count long tmp2 = 1; tmp2 1 long tmpsum = 0; tmpsum 0 for (int i = 0; i < count-1; i++) {
            tmp2 *=26;
            tmpsum += tmp2;
        } int i = 0; int i = 0; i 0 i < count-1 i count-1 count 1 i++ i++ i {
            tmp2 *=26;
            tmpsum += tmp2;
        } {
            tmp2 *=26;
            tmpsum += tmp2;
        } tmp2 *=26 tmp2 26 tmpsum += tmp2 tmpsum tmp2 n -= tmpsum n tmpsum n-- n long twosix = 1; twosix 1 for (int i = 0; i < count-1; i++) {
            twosix *= 26;
        } int i = 0; int i = 0; i 0 i < count-1 i count-1 count 1 i++ i++ i {
            twosix *= 26;
        } {
            twosix *= 26;
        } twosix *= 26 twosix 26 String str = ""; str "" for (int i = 0; i < count; i++) {
            long tmp3 = n / twosix;
            // System.out.println(tmp3);
            char c = (char)(tmp3 + 'a');
            str += c;
            // System.out.println(c);
            
            n -= twosix * tmp3;
            twosix /= 26;
            // System.out.println(n);
        } int i = 0; int i = 0; i 0 i < count i count i++ i++ i {
            long tmp3 = n / twosix;
            // System.out.println(tmp3);
            char c = (char)(tmp3 + 'a');
            str += c;
            // System.out.println(c);
            
            n -= twosix * tmp3;
            twosix /= 26;
            // System.out.println(n);
        } {
            long tmp3 = n / twosix;
            // System.out.println(tmp3);
            char c = (char)(tmp3 + 'a');
            str += c;
            // System.out.println(c);
            
            n -= twosix * tmp3;
            twosix /= 26;
            // System.out.println(n);
        } long tmp3 = n / twosix; tmp3 n / twosix n twosix char c = (char)(tmp3 + 'a'); c (char)(tmp3 + 'a') tmp3 'a' str += c str c n -= twosix * tmp3 n twosix * tmp3 twosix tmp3 twosix /= 26 twosix 26 System.out.println(str) System.out.println System.out System System.out str String[] args args public class Main {
    public static void main(String[] args) throws Exception {
        // Your code here!
        Scanner sc = new Scanner(System.in);
        long n = sc.nextLong();
        
        int count = 0;
        long ts = 1;
        long tssum = 0;
        for (int i = 2; i < 100; i++) {
            if (n <= tssum) {
                break;
            } else {
                ts *= 26;
                tssum += ts;
                count++;
            }
        }
        
        // System.out.println(count);
        
        long tmp2 = 1;
        long tmpsum = 0;
        for (int i = 0; i < count-1; i++) {
            tmp2 *=26;
            tmpsum += tmp2;
        }
        n -= tmpsum;
        n--;
        
        // System.out.println(n);
        
        long twosix = 1;
        for (int i = 0; i < count-1; i++) {
            twosix *= 26;
        }
        
        String str = "";
        for (int i = 0; i < count; i++) {
            long tmp3 = n / twosix;
            // System.out.println(tmp3);
            char c = (char)(tmp3 + 'a');
            str += c;
            // System.out.println(c);
            
            n -= twosix * tmp3;
            twosix /= 26;
            // System.out.println(n);
        }
        
        System.out.println(str);
    }
} public class Main {
    public static void main(String[] args) throws Exception {
        // Your code here!
        Scanner sc = new Scanner(System.in);
        long n = sc.nextLong();
        
        int count = 0;
        long ts = 1;
        long tssum = 0;
        for (int i = 2; i < 100; i++) {
            if (n <= tssum) {
                break;
            } else {
                ts *= 26;
                tssum += ts;
                count++;
            }
        }
        
        // System.out.println(count);
        
        long tmp2 = 1;
        long tmpsum = 0;
        for (int i = 0; i < count-1; i++) {
            tmp2 *=26;
            tmpsum += tmp2;
        }
        n -= tmpsum;
        n--;
        
        // System.out.println(n);
        
        long twosix = 1;
        for (int i = 0; i < count-1; i++) {
            twosix *= 26;
        }
        
        String str = "";
        for (int i = 0; i < count; i++) {
            long tmp3 = n / twosix;
            // System.out.println(tmp3);
            char c = (char)(tmp3 + 'a');
            str += c;
            // System.out.println(c);
            
            n -= twosix * tmp3;
            twosix /= 26;
            // System.out.println(n);
        }
        
        System.out.println(str);
    }
} Main
import java.util.*;

public class Main {
    public static void main(String[] args) throws Exception {
        // Your code here!
        Scanner sc = new Scanner(System.in);
        long n = sc.nextLong();
        
        int count = 0;
        long ts = 1;
        long tssum = 0;
        for (int i = 2; i < 100; i++) {
            if (n <= tssum) {
                break;
            } else {
                ts *= 26;
                tssum += ts;
                count++;
            }
        }
        
        // System.out.println(count);
        
        long tmp2 = 1;
        long tmpsum = 0;
        for (int i = 0; i < count-1; i++) {
            tmp2 *=26;
            tmpsum += tmp2;
        }
        n -= tmpsum;
        n--;
        
        // System.out.println(n);
        
        long twosix = 1;
        for (int i = 0; i < count-1; i++) {
            twosix *= 26;
        }
        
        String str = "";
        for (int i = 0; i < count; i++) {
            long tmp3 = n / twosix;
            // System.out.println(tmp3);
            char c = (char)(tmp3 + 'a');
            str += c;
            // System.out.println(c);
            
            n -= twosix * tmp3;
            twosix /= 26;
            // System.out.println(n);
        }
        
        System.out.println(str);
    }
}
