int b,c,d,e=0,total=300, sum=0.0;
float percentage=0;
string a;
cout<<"******Welcome to the Student Grading Calculation System******" <<endl;
cout<<"\n";
cout<< "Do you want to Calculate your Grades?"<<endl;
cout<<"Enter y for yes or n for no" <<endl;
while(e<5){
cin>> a;
if(a=="y"){
cout<<"Enter your Math Marks \n";
cin>> b;
cout<<"Enter your Science Marks \n";
cin >> c;
cout<<"Enter your English Marks \n";
cin>> d;
sum = b+c+d;
cout<< "your Obtained marks are = " << sum <<endl;
percentage = sum*100/total;
cout << "Percentage = " << percentage << "%" << endl;
cout<<"\n";
cout<<"Do you want Further Calculation of your Grades ? " << endl;
e++;
}else {
if(a=="n"){
cout <<"Thank you so much for using Student Calculation System " << endl;
return 1;