// yukicoder: No.254 文字列の構成
// 2019.7.10 bal4u

#include <stdio.h>
#include <math.h>

#if 1
#define gc() getchar_unlocked()
#define pc(c) putchar_unlocked(c)
#else
#define gc() getchar()
#define pc(c) putchar(c)
#endif

int in()    // 非負整数の入力
{
	int n = 0, c = gc();
	do n = 10 * n + (c & 0xf); while ((c = gc()) >= '0');
	return n;
}

int calc(int n, int a, int b) {
	int k = (int)sqrt((double)n);
	n -= k*k;
	pc(a); while (--k) pc(b), pc(a);
	return n;
}
	
int main()
{
	int a, N;

	a = 'a', N = in();
	while (N) N = calc(N, a, a+1), a += 2;
	pc('\n');
	return 0;
}