#include <stdio.h>
#include <stdlib.h>
int main() {
    int x;
    if (scanf("%d", &x) != EOF) {
        int charnum = 0;
        char* answer = (char*)malloc(sizeof(char) * x);
        int answerIdx = 0;
        while(x != 0) {
            if(x % 2 == 1) {
                x--;
                answer[answerIdx] = charnum + 'a';
                answerIdx++;
            } else {
                x /= 2;
                charnum++;
            }
        }
        printf("%s\n", answer);
    } else {
        printf("no input\n");
    }
    return 0;
}