Conway's Game of Life in Python - Competitive Programming - how to optimize

Question

I am solving Game of Life problem on csacademy and I can't manage to beat the time on larger inputs. Any help on optimizing the code?

I tried changing things, like using np.array() instead of list, and not converting the original input to 1s and 0s (original is '*' and '-', and needs to be printed that way).

from copy import deepcopy
import numpy as np
aliveToDead = {0, 1, 4, 5, 6, 7, 8}
deadToAlive = {3}


def countNeighbors(M, n, m, i, j):
    s = M[i, (j + 1) % m] + M[i, j - 1] + M[(i + 1) % n, j] + M[i - 1, j]
    s += M[i - 1, j - 1] + M[(i + 1) % n, (j + 1) % m] + M[i - 1, (j + 1) % m] + M[(i + 1) % n, j - 1]
    return s


def gameOfLife(mat, n, m, C):
    cells = deepcopy(mat)
    for c in range(C):
        for i in range(n):
            for j in range(m):
                neighbors = countNeighbors(mat, n, m, i, j)
                if mat[i, j] == 1 and neighbors in aliveToDead:
                    cells[i, j] = 0
                elif mat[i, j] == 0 and neighbors in deadToAlive:
                    cells[i, j] = 1
        mat = deepcopy(cells)
    return mat


def buildList(n):
    return np.array([[0 if x == '-' else 1 for x in input()] for i in range(n)])


def printResult(mat):
    mat = mat.astype(str)
    mat[mat == "1"] = '*'
    mat[mat == "0"] = '-'
    for row in mat:
        print(*row, sep="")


def main():
    n, m, c = map(int, input().split())
    mat = buildList(n)
    result = gameOfLife(mat, n,  m, c)
    printResult(result)


if __name__ == "__main__":
    main()