n, m = [int(i) for i in input().split()]
p = [[int(i) for i in input().split()] for j in range(n)]
bfs = [[1000000000 for i in range(m)] for j in range(n)]
bfs[0][0] = p[0][0]

queue = [[0, 0]]
while(len(queue) > 0):
    a = queue[0]
    x = a[1]
    y = a[0]
    del queue[0]
    if(y > 0):
        if(bfs[y - 1][x] > bfs[y][x] + p[y - 1][x]):
            queue.append([y - 1, x])
            bfs[y - 1][x] = bfs[y][x] + p[y - 1][x]
    if(y < n - 1):
        if(bfs[y + 1][x] > bfs[y][x] + p[y + 1][x]):
            queue.append([y + 1, x])
            bfs[y + 1][x] = bfs[y][x] + p[y + 1][x]
    if(x > 0):
        if(bfs[y][x - 1] > bfs[y][x] + p[y][x - 1]):
            queue.append([y, x - 1])
            bfs[y][x - 1] = bfs[y][x] + p[y][x - 1]
    if(x < m - 1):
        if(bfs[y][x + 1] > bfs[y][x] + p[y][x + 1]):
            queue.append([y, x + 1])
            bfs[y][x + 1] = bfs[y][x] + p[y][x + 1]
print(bfs[n - 1][m - 1])