Write a program in C++ to create and display unique three-digit number using 1, 2, 3, 4. Also count how many three-digit numbers are there

#include <iostream>
using namespace std;

void revOfString(const string& a);

int main()
{
    string str;
    cout << "\n\n Create and display the unique three-digit number using 1, 2, 3, 4:\n";
	cout << "-------------------------------------------------------------------\n";
	cout<<" The three-digit numbers are: "<<endl;
		int amount = 0;
		cout<<" ";
		for(int i = 1; i <= 4; i++)
		{
			for(int j = 1; j <= 4; j++)
			{
				for(int k = 1; k <= 4; k++)
				{
					if(k != i && k != j && i != j)
					{
						amount++;
						cout<<i <<j<<k<<" ";
					}
				}
			}
		}
		cout<<endl<<" Total number of the three-digit-number is: "<< amount<<endl<<endl;
}