import heapq
        
N = int(input())
weight = []
for _ in range(N):
    weight.append([int(d) for d in input().split(" ")])
dist = [[float('inf') for _ in range(N)] for _ in range(N)]

dist[0][0] = weight[0][0]

q = [(dist[0][0], (0, 0))]
heapq.heapify(q)

while q:
    d, v = heapq.heappop(q)
    
    if d > dist[v[1]][v[0]]:
        continue
    
    if v[0] > 0: #left
        new_d = d + weight[v[1]][v[0]-1]
        if new_d < dist[v[1]][v[0]-1]:
            dist[v[1]][v[0]-1] = new_d
            heapq.heappush(q, (new_d, (v[0]-1,v[1])))
    if v[0] < N - 1: #right
        new_d = d + weight[v[1]][v[0]+1]
        if new_d < dist[v[1]][v[0]+1]:
            dist[v[1]][v[0]+1] = new_d
            heapq.heappush(q, (new_d, (v[0]+1,v[1])))
    if v[1] > 0: #up
        new_d = d + weight[v[1]-1][v[0]]
        if new_d < dist[v[1]-1][v[0]]:
            dist[v[1]-1][v[0]] = new_d
            heapq.heappush(q, (new_d, (v[0],v[1]-1)))
    if v[1] < N - 1: #down
        new_d = d + weight[v[1]+1][v[0]]
        if new_d < dist[v[1]+1][v[0]]:
            dist[v[1]+1][v[0]] = new_d
            heapq.heappush(q, (new_d, (v[0],v[1]+1)))
            
print(dist[-1][-1])