import std.stdio, std.array, std.string, std.conv, std.algorithm; import std.typecons, std.range, std.random, std.math, std.container; import std.numeric, std.bigint, core.bitop; const long MOD = 10^^9 + 7; const long BASE = 97; void main() { auto N = readln.chomp.to!int; int[] B; for (int i = 0, M = N; M > 0; i+=1, M/=2) if (M % 2) B ~= i; int s = 0; string ans = ""; char c = 'a'; foreach (i; 0..B.length) { B[i] -= s; if (i + 1 == B.length) { foreach (_; 0..B[i]) ans ~= c; } else { foreach (_; 0..B[i]+1) ans ~= c; s += B[i]; c += 1; } } auto sna = ans.dup; sna.reverse(); ans = ans.to!string ~ "xyz" ~ sna.to!string; ans.writeln; }