#include <bits/stdc++.h>
int main(void) {
  int n;
  scanf("%d", &n);
  int tmp = n;
  int c, d = 0, ans[11];
  if (tmp >= 26) {
    while (tmp >= 26) {
      c = tmp % 26;
      tmp = tmp / 26;
      ans[d] = c;
      d++;
    }
    ans[d] = tmp;
    d++;
  } else {
    ans[0] = tmp;
    d = 1;
  }
  for (int i = d - 1; i >= 0; i--) {
    if (ans[i] == 0) {
      printf("%c", 122);
    } else {
      printf("%c", ans[i] + 96);
    }
  }
  printf("\n");
  return 0;
}
