#include <bits/stdc++.h>
using namespace std;
int cost[1005];
void init() {
  cost[0] = cost[1] = 0;
  for (int i = 2; i < 1005; i++) {
    cost[i] = (i - 1) * i / 2;
  }
}
void solve(int n, int x) {
  if (n == 0 || x > 26) return;
  char a = 'a' + x;
  int i;
  for (i = 0; i < 1005; i++) {
    if (cost[i] > n) {
      for (int j = 0; j < i - 1; j++) {
        printf("%c", a);
      }
      break;
    }
  }
  n -= cost[i - 1];
  solve(n, x + 1);
  return;
}
int main() {
  init();
  int n;
  while (~scanf("%d", &n)) {
    if (n == 0) {
      printf("a\n");
      continue;
    }
    solve(n, 0);
    printf("\n");
  }
}
