import java.io.IOException; import java.io.InputStream; import java.util.Arrays; import java.util.Comparator; import java.util.NoSuchElementException; public class Main { public static void main(String[] args) { new Main().run(); } void run() { Scanner sc = new Scanner(); long N = sc.nextLong(); String ans = ""; long[] comb = new long[100000]; for (long i = 0; i < comb.length; ++i) { // aがi+1個,bがi個の時、 comb[(int) i] = (i + 2) * (i + 1) / 2 + (i + 1) * i / 2; } for (int i = 0; i < 27 && N > 0; ++i) { int j = 0; while (comb[j + 1] <= N) { ++j; } String a = String.valueOf((char) ('a' + i)); String b = String.valueOf((char) ('a' + i + 1)); String add = ""; for (int k = 0; k < j; ++k) { add = add + a + b; } add = add + a; ans = ans + add; N -= comb[j]; } if (N != 0) throw new AssertionError(); System.out.println(ans); } void tr(Object... objects) { System.out.println(Arrays.deepToString(objects)); } class Scanner { private final InputStream in = System.in; private final byte[] buffer = new byte[1024]; private int ptr = 0; private int buflen = 0; private boolean hasNextByte() { if (ptr < buflen) { return true; } else { ptr = 0; try { buflen = in.read(buffer); } catch (IOException e) { e.printStackTrace(); } if (buflen <= 0) { return false; } } return true; } private int readByte() { if (hasNextByte()) return buffer[ptr++]; else return -1; } private boolean isPrintableChar(int c) { return 33 <= c && c <= 126; } public boolean hasNext() { while (hasNextByte() && !isPrintableChar(buffer[ptr])) ptr++; return hasNextByte(); } public String next() { if (!hasNext()) throw new NoSuchElementException(); StringBuilder sb = new StringBuilder(); int b = readByte(); while (isPrintableChar(b)) { sb.appendCodePoint(b); b = readByte(); } return sb.toString(); } public long nextLong() { if (!hasNext()) throw new NoSuchElementException(); long n = 0; boolean minus = false; int b = readByte(); if (b == '-') { minus = true; b = readByte(); } if (b < '0' || '9' < b) { throw new NumberFormatException(); } while (true) { if ('0' <= b && b <= '9') { n *= 10; n += b - '0'; } else if (b == -1 || !isPrintableChar(b)) { return minus ? -n : n; } else { throw new NumberFormatException(); } b = readByte(); } } public int nextInt() { long nl = nextLong(); if (nl < Integer.MIN_VALUE || nl > Integer.MAX_VALUE) throw new NumberFormatException(); return (int) nl; } public double nextDouble() { return Double.parseDouble(next()); } } }