Задача В

A, B, C = 0, 1, 2

n = int(input())
time = [list(map(int, input().split())) for i in range(n)]
min_time = [None] * n
min_time[0] = time[0][A]
if n > 1:
    min_time[1] = min(min_time[0] + time[1][A], time[0][B])
if n > 2:
    min_time[2] = min(min_time[1] + time[2][A], min_time[0] + time[1][B],
                        time[0][C])
for i in range(3, n):
    min_time[i] = min(min_time[i - 1] + time[i][A], min_time[i - 2] +
                        time[i - 1][B], min_time[i - 3] + time[i - 2][C])
print(min_time[n - 1])

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Задача С

n, m = map(int, input().split())
variants = [([None] * m) + [0, 0] for i in range(n)] + [[0] * m
                                                        for i in range(2)]
for i in range(n):
    for j in range(m):
        if i == 0 and j == 0:
            variants[i][j] = 1
        else:
            variants[i][j] = variants[i - 2][j - 1] + variants[i - 1][j - 2]
print(variants[n - 1][m - 1])