main.py

import sys


def solve(data: str) -> str:
    tokens = list(map(int, data.split()))
    if not tokens:
        return ""
    it = iter(tokens)
    n = next(it)
    days_total = next(it)
    diff = [0] * (days_total + 3)
    for _ in range(n):
        left = next(it)
        right = next(it)
        diff[left] += 1
        diff[right + 1] -= 1
    active = 0
    max_open = -1
    first_peak = 0
    merged = []
    start = None
    for day in range(1, days_total + 1):
        active += diff[day]
        if active > max_open:
            max_open = active
            first_peak = day
        if active > 0 and start is None:
            start = day
        if active == 0 and start is not None:
            merged.append((start, day - 1))
            start = None
    if start is not None:
        merged.append((start, days_total))
    merged_text = "|".join(f"{left}-{right}" for left, right in merged) if merged else "NONE"
    return "\n".join(
        [
            f"max_open={max_open}",
            f"first_peak_day={first_peak}",
            f"merged={merged_text}",
        ]
    )


if __name__ == "__main__":
    sys.stdout.write(solve(sys.stdin.read()).strip())
    sys.stdout.write("\n")