n = int(input())
grid = [list(map(int, input().split())) for _ in range(n)]
dp = [[0] * n for _ in range(n)]
dp[0][0] = grid[0][0]
for i in range(1, n):
    dp[i][0] = dp[i - 1][0] + grid[i][0]
for j in range(1, n):
    dp[0][j] = dp[0][j - 1] + grid[0][j]
for i in range(1, n):
    for j in range(1, n):
        dp[i][j] = min(dp[i - 1][j], dp[i][j - 1]) + grid[i][j]
print(dp[n - 1][n - 1])