#include <iostream>
#include <cstring>

using namespace std;

// find the logical error
int main()
{
   int grade;
   string letter;
   cout<<"Enter your final score: ";
   cin>>grade;

   if(grade = 100)
   {
      letter = "Perfect A";
   }
   else if(grade > 89)
   {
      letter = "A";
   }
   else if(grade > 79)
      letter = "B";
   else if(grade > 69)
      letter = "C";
   else if(grade > 59)
      letter = "D";
   else if(grade > 49)
      letter = "F";

   cout<<"Your letter grade = "<<letter<<endl;

   return 0;
}