Write a program to display the grades A,B,C,D,E,F and S , according to the marks obtained.

#include<iostream> 
using namespace std; 
int main() 
{  
	int marks,m;					// declaring the variables
	cout<<"enter marks: "; 
	cin>>marks;					// taking the mrks 
	m=marks/10;
	switch(m)
	{	case 0:
		case 1:
		case 2:
		case 3:
			cout<<"Grade is F";  break;
		case 4:
			cout<<"Grade is E";  break;   // grade conversion 
		case 5:
			cout<<"Grade is D";  break;
		case 6:
			cout<<"Grade is C";  break;
		case 7:
			cout<<"Grade is B";
			break;
		case 8:
			cout<<"Grade is A";
			break;
		case 9:
		case 10:
			cout<<"Grade is S";
			break;
		default:
			cout<< "incorrect number";
			break;        
		}
		return 0;
	}