#include <stdio.h>
#include <stdlib.h>

void convertToTitle(int n) {
    if (n < 1) {
        printf("-1\n");
        return;
    }

    char result[20]; 
    int index = 0;

    while (n > 0) {
        n--;  
        result[index++] = (n % 26) + 'A';
        n /= 26;
    }

    for (int i = index - 1; i >= 0; i--) {
        putchar(result[i]);
    }
    printf("\n");
}