Project Euler：Problem 47 Distinct primes factors

The first two consecutive numbers to have two distinct prime factors are:

14 = 2 × 7

15 = 3 × 5

The first three consecutive numbers to have three distinct prime factors are:

644 = 22 × 7 × 23

645 = 3 × 5 × 43

646 = 2 × 17 × 19.

Find the first four consecutive integers to have four distinct prime factors. What is the first of these numbers?

#include <iostream>
#include <map>
using namespace std;

int factors(int n)
{
	map<int, int>mp;
	int i = 2;
	while (n > 1)
	{
		if (n%i == 0)
		{
			mp[i]++;
			n /= i;
		}
		else
			i++;
	}
	return mp.size();
}

int main()
{
	for (int i = 20; i <= 1000000; i++)
	{
		if (factors(i) == 4)
		{
			if (factors(i + 1) == 4)
			{
				if (factors(i + 2) == 4)
				{
					if (factors(i + 3) == 4)
					{
						cout << i << endl;
						break;
					}
				}
			}
		}
	}
	system("pause");
	return 0;
}