Interval Coverage

You are given several intervals represented as pairs of integers [start, end]. Your task is to determine how much of the number line is covered by at least one of the intervals. The coverage is defined as the total length of the segments covered by at least one interval. Input format: - First line contains an integer n (1 ≤ n ≤ 100): number of intervals. - Next n lines each containing two integers start and end, separated by a space (0 ≤ start < end ≤ 10^9). Output format: - Print a single integer representing the total length covered by at least one interval. Example: Input: 3 1 3 2 4 5 7 Output: 6