class flashcards extends basic { 

// Main program to monitor a series of flashcard practice sessions 
   public static void main (String[] args) throws Exception { 
       input in = new input(); 
       output out = new output(); 
       String answer=""; int n=0; 
       out.write("Do you want a flashcard drill (y or n)?"); 
       answer = in.readword(); 
       while (answer.equals("y")) { 
         out.write("How many flashcards do you want to see?"); 
         n = in.readint(); 
         int nCorrect = Practice(in, out, n); 
         out.writeln ("You have solved " + nCorrect + 
                      " out of " + n + " problems correctly!"); 
         out.write("Do you want another drill (y or n)?"); 
         answer = in.readword(); 
       } 
   } 

// Monitor a practice session for a series of 'nCards' problems; 
// return the number of problems that the user solves correctly. 
   static int Practice (input in, output out, int nCards) throws Exception { 
     int c = 0, max = 100; 
     random select = new random(1,max); 
     for (int i=1; i<=nCards; i++) { 
       int a = select.readint(); 
       int b = select.readint(); 
       boolean gotItRight = SolveProblem(in, out, a, b); 
       if (gotItRight) 
         c = c + 1; 
     } 
     return c; 
   } 

// Monitor a single interaction for the problem 'a + b' 
// and return 'true' if the answer is correct. 
   static boolean SolveProblem (input in, output out, int a, int b) throws Exception { 
     out.writeln("What is " + a + " + " + b + "?"); 
     int sum = in.readint(); 
     if (sum != a+b) 
       { out.writeln(sum + " is incorrect"); return false; } 
     else 
       { out.writeln(sum + " is correct"); return true; } 
   } 
}