from typing import List


def find_substr_in_list(
    substr: str, strs: List[str], start_pos: int = 0, exact: bool = False
) -> int:
    """Find a specific substring within the given list of strings,
    starting from a given position."""
    for i, s in enumerate(strs):
        if i < start_pos:
            continue
        # Exact match
        if exact and substr == s:
            return i
        # Contain
        if not exact and substr in s:
            return i

    return -1