from typing import List


def solve(nels: int, arr: List[int]) -> bool:
    """Check if a sequence is convertable to a strictly increasing one.

    Parameters
    ----------
    nels: int - number of elements
    arr: Sequence - sequence to convert

    Returns
    -------
    bool
    """
    nels = len(arr)
    for i in range(nels - 2, -1, -1):
        if arr[i] >= arr[i + 1]:
            arr[i] = arr[i + 1] - 1
            if arr[i] < 0:
                return False
    return True