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

// Function to convert a positive integer to Excel column string
void intToExcelCol(int n, char *result) {
    int index = 0;
    char temp[10];  // Enough for large n
    
    while (n > 0) {
        n--;  // Decrement to make zero-based
        temp[index++] = 'A' + (n % 26);
        n /= 26;
    }
    
    // Reverse the string into result
    for (int i = 0; i < index; i++) {
        result[i] = temp[index - i - 1];
    }
    result[index] = '\0';
}

int isInteger(const char *s) {
    // Check if string s is a valid