030608 inclass bf mid get grade.cpp

this code is code c++. have many lesson

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

int main()
{
	int score,grade;
	cout <<"Input your score : ";
	cin >> score;
	
	if (score<0)
	{
		cout << "ERROR" <<endl;
    }
	else if (score<=59)
    {
		grade = 1;
    }
	else if (score<=69)
	{
		grade = 2;
    }	
	else if (score<=79)
    {	
		grade = 3;
    }	
	else if (score<=89)
    {	
		grade = 4;
    }	
	else if (score<=100)
    {
		grade = 5;
    }
	else 
		cout << "ERROR" <<endl;
		
switch(grade){
		case 1 : cout << "Your grade is F" <<endl;
		break;
		case 2 : cout << "Your grade is D" <<endl;
		break;
		case 3 : cout << "Your grade is C" <<endl;
		break;
		case 4 : cout << "Your grade is B" <<endl;
		break;
		case 5 : cout << "Your grade is A" <<endl;
		break;
        default:cout << endl;
                 
    }

	system ("Pause");
	return 0;
}