import std.algorithm, std.conv, std.range, std.stdio, std.string;
import std.math;      // math functions

void main()
{
  auto n = readln.chomp.to!int;

  auto aba = true;
  while (n > 15) {
    auto k = n.to!real.sqrt.floor.to!int;
    if (aba) {
      foreach (_; 0..k-1) write("ab");
      write("a");
    } else {
      foreach (_; 0..k-1) write("cd");
      write("c");
    }
    n -= k * k;
    aba = !aba;
  }

  writeln("efghijklmnopqrs"[0..n]);
}