c++(cpp)_성적 산출

#include <iostream>
using namespace std;

int main()
{
	char grade = 'X';
	int score;
	cout << "Enter your score : ";
	cin >> score;

	if (score <= 100 && score >= 0)
	{
		if (score >= 90)
		{
			grade = 'A';
			cout << "Your grade is " << grade << endl;
		}

		else if (score >= 80 && score < 90)
		{
			grade = 'B';
			cout << "Your grade is " << grade << endl;
		}

		else if (score >= 70 && score < 80)
		{
			grade = 'C';
			cout << "Your grade is " << grade << endl;
		}

		else if (score >= 60 && score < 70)
		{
			grade = 'D';
			cout << "Your grade is " << grade << endl;
		}

		else if (score < 60)
		{
			grade = 'F';
			cout << "Your grade is " << grade << endl;
		}
	}
	else
	{
		cout << "The score (" << score << ") is invalid" << endl;
	}

	return 0;
}