Grade Tier

**Description:** Given a score n (0 ≤ n ≤ 10, real number), print: - A if n ≥ 8.0 - B if 6.5 ≤ n < 8.0 - C if 5.0 ≤ n < 6.5 - D if n < 5.0 **Input:** One real number n. **Output:** One letter {A, B, C, D}. **Example:** 8.0 → A; 6.5 → B; 4.9 → D.