#include <iostream>

using namespace std;

int main() {
    int height;

    // Prompt the user for input
    cout << "Enter an integer (3-25):\n ";//print out instruction for the user
    cin >> height; 

    // Validate the input
    if (height < 3 || height > 25) {
        cout << "Invalid input! Please enter an integer between 3 and 25.\n" << endl;//to catch error
        return 1; // Exit with an error code if found true
    }

    // Calculate the character to use (ones digit of the height)
    char character = (height % 10) + '0';

   // Draw the isosceles triangle
    for (int i = 1; i <= height; ++i) { // Outer loop controls the rows
        // Print spaces for alignment
        for (int j = 1; j <= height - i; ++j) {
            cout << " ";
        }
        // Print the characters to form the triangle
        for (int j = 1; j <= (2 * i - 1); ++j) {
            cout << character;
        }
        cout << endl; // Move to the next line after each row
    }

            
    return 0;
}