Solo Shift Bonus

At a 24-hour facility, N shifts are scheduled. A worker earns a 'Concentration Bonus' for every minute they are the only person on duty. Given the start and end times of all shifts, calculate the total duration covered by exactly one shift. Input Format: - An integer N. - N lines, each containing S and E. Output Format: - A single integer representing the total 'solo' time. Example: Input: 2 1 10 5 15 Output: 9 Explanation: 1 to 5 (Solo), 5 to 10 (Overlap), 10 to 15 (Solo). Total = 4 + 5 = 9.