Clinic: The Vanishing Total

**Bài toán.** Sum n integers; print the total. |a[i]| ≤ 10^9, n ≤ 200000, so the total reaches ~2·10^14. **The submission below gets Wrong Answer on the largest test.** Find the counterexample input, name the failure class, and FIX the program. ``cpp int s = 0; for each x: s += x; // reading ints ``