lines = (x.strip() for x in open("input.txt")) reserved = [] def parse_binary_string(string: str, ones): length = len(string) - 1 cnt = 0 for idx, val in enumerate(string): cnt += 2 ** (length-idx) if val == ones else 0 return cnt for line in lines: row = parse_binary_string(line[:7], ones="B") col = parse_binary_string(line[7:], ones="R") num = row * 8 + col reserved.append(num) reserved = sorted(reserved) for i in range(len(reserved) - 1): if reserved[i+1] - reserved[i] == 2: print(reserved[i]+1)