N, M = map(int, input().split())
array_first = [list(map(int, input().split())) for i in range(N)]
array_second= [[0 for i in range(M)] for j in range(N)]
array_second[0][0] = array_first[0][0]
for i in range(1, M):
    array_second[0][i] = array_second[0][i - 1] + array_first[0][i]
for i in range(1, N):
    array_second[i][0] = array_second[i - 1][0] + array_first[i][0]
for i in range(1, N):
    for j in range(1, M):
        array_second[i][j] = array_first[i][j] + min(array_second[i - 1][j], array_second[i][j - 1])
print(array_second[N - 1][M - 1])