Ugly Numbers

Ugly numbers are numbers whose only prime factors are 2, 3 or 5. The sequence
1, 2, 3, 4, 5, 6, 8, 9, 10, 12, 15, …
shows the first 11 ugly numbers. By convention, 1 is included.
Write a program to find and print the 1500’th ugly number.

Input
There is no input to this program.

Output
Output should consist of a single line as shown below, with ‘’ replaced by the number computed.

Sample Output
The 1500’th ugly number is .

#include <iostream>
#include <queue>
#include <vector>
#include <set>
#include <stdio.h>

typedef long long LL;

int sam[3] = {2, 3, 5};

using namespace std;

int main()
{
    priority_queue< LL, vector<LL>, greater<LL> > ugly_numbers;
    set<LL> numbers;
    numbers.insert(1);
    ugly_numbers.push(1);
    for(int i = 1; ; i++){
        LL x = ugly_numbers.top();
        if(i == 1500)
        {
            cout <<  "The 1500'th ugly number is " << x << "." << endl;
            break;
        }
        ugly_numbers.pop();
        for(int j=0; j<3; j++){
            if(numbers.count(sam[j]*x) == 1)
                continue;
            else{
                numbers.insert(sam[j]*x);
                ugly_numbers.push(sam[j]*x);
            }
        }
    }
    return 0;
}