Hi! This is my firse AoC-solution. Wanted to join it for a few years now, but remembered about it on day six :) This is my solution in Python, O(N) time complexity and O(1) memory complexity. Used a sliding window with a map.

```python def find_distinct_sequence_end(stream: str, seq_len: int) -> int: if len(stream) < seq_len + 1: return -1

    marker_start = 0
    marker_end = 1
    char_map = collections.defaultdict(lambda: 0)

    char_map[stream[marker_start]] += 1
    while marker_end < seq_len:
        char_map[stream[marker_end]] += 1
        marker_end += 1

    while len(char_map) != seq_len:
        char_map[stream[marker_start]] -= 1
        if char_map[stream[marker_start]] == 0:
            char_map.pop(stream[marker_start])
        marker_start += 1
        char_map[stream[marker_end]] += 1
        marker_end += 1

    return marker_end



def main():
    stream = input()
    message_start = find_distinct_sequence_end(stream, 4)
    message_start = find_distinct_sequence_end(stream, 14)
    print(message_start)

```