Why is this not giving me a letter grade when run?

#include #include

using namespace std;

int main() { double grade1, grade2, grade3, grade4, total;

cout << "please enter the first grade : "; cin >> grade1; cout << "Please enter the second grade : "; cin >> grade2; cout << "Please enter the third grade : "; cin >> grade3; cout << "Please enter the fourth grade : "; cin >> grade4;

total = (grade1 + grade2 + grade3 + grade4) / 4;

cout << "The average grade is : " << setprecision(6) << total << endl;

const int A_score = 90, B_score = 80, C_score = 70, D_score = 60;

int testScore;

cin >> testScore;

if (testScore >= A_score) cout << "Your grade is A. "; else if (testScore >= B_score) cout << "Your grade is B. "; else if (testScore >= C_score) cout << "Your grade is C. "; else if (testScore >= D_score) cout << "Your grade is D. "; else if (testScore >= 0) cout << "Your grade is F. "; else cout << "invalid test score. ";

return 0; }