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// implement by priority queue using STL set
// CPU time = 0.008

#include <cstdio>
#include <set>
using namespace std; 

int main(){
	int counter=0;
	long long int tmp; 
	set<long long int> ugly_set;
	set<long long int>::iterator i;
	
	ugly_set.insert(1);
	
	while(counter<1500){
		i=ugly_set.begin();
		tmp=*i;
		ugly_set.insert(tmp*2); 
		ugly_set.insert(tmp*3);
		ugly_set.insert(tmp*5);
		ugly_set.erase(tmp);
		counter++; 
	}
	
	printf("The 1500'th ugly number is %lld.\n", tmp);  
}