#include <stdio.h>

// Function prototype
char getGrade(int score);

// Function definition
/**
 * Function Name: getGrade
 * 
 * Function Block:
 * Determines the letter grade based on the given score.
 * 
 * @param score The test score (0-100).
 * @return The letter grade corresponding to the score, or 'I' for invalid scores.
 */
char getGrade(int score) {
    if (score < 0 || score > 100) {
        return 'I'; // Invalid score
    } else if (score >= 90) {
        return 'A';
    } else if (score >= 80) {
        return 'B';
    } else if (score >= 70) {
        return 'C';
    } else if (score >= 60) {
        return 'D';
    } else {
        return 'F';
    }
}

int main() {
    int score;

    // Test cases
    score = 95;
    printf("Score: %d, Grade: %c\n", score, getGrade(score)); // Expected output: A

    score = 85;
    printf("Score: %d, Grade: %c\n", score, getGrade(score)); // Expected output: B

    score = 75;
    printf("Score: %d, Grade: %c\n", score, getGrade(score)); // Expected output: C

    score = 65;
    printf("Score: %d, Grade: %c\n", score, getGrade(score)); // Expected output: D

    score = 55;
    printf("Score: %d, Grade: %c\n", score, getGrade(score)); // Expected output: F

    score = -5;
    printf("Score: %d, Grade: %c\n", score, getGrade(score)); // Expected output: I

    score = 105;
    printf("Score: %d, Grade: %c\n", score, getGrade(score)); // Expected output: I

    return 0;
}