Smart people's game improvement: Chapter 3, Lesson 2: "Number of Tongtong" (number)

#include <iostream> 
#include <cstdio>
using namespace std;
long long n,i,j,s=2;
int t(int a)
{
	for (j=2;j*j<=a;j++)
		if (a%j==0)
			return 0;
	if (a>1)
		return 1;
	return 0;
}
int main()
{
	cin >>n;
	for (i=2;i*i<=n;i++)
		if (n%i==0)
			s+=2;
	i--;
	if (i*i==n && !t(i))
		s--;
	if (s==4)
		cout <<"It's a Tongtong number.";
	else
		cout <<"It's not a Tongtong number.";
	return 0;
}