Fissure Puzzle Easy

Problem

There is a grid of $N \ times N$ cells. Initially all cells are white. Follow the steps below to increase the number of black squares.

Select one white cell from the cells that are even-numbered from the top and even-numbered from the left. The selected square turns black. Further, the adjacent white squares also change to black in a chain reaction in each of the vertical and horizontal directions of the squares. This chain continues until there are no white cells in that direction. (An example is shown below)

□□□□□□□□□ □□□□□□□□□ □□□□□□□□□ □□□□□□□□□ □□□□□□□□□ □□□□□□□□□ □□□□□□□□□ □□□□□□□□□ □□□□□□□□□ ↓ Select the 4th from the top and the 6th from the left □□□□□ ■ □□□ □□□□□ ■ □□□ □□□□□ ■ □□□ ■■■■■■■■■ □□□□□ ■ □□□ □□□□□ ■ □□□ □□□□□ ■ □□□ □□□□□ ■ □□□ □□□□□ ■ □□□ ↓ Select the second from the top and the second from the left □ ■ □□□ ■ □□□ ■■■■■■ □□□ □ ■ □□□ ■ □□□ ■■■■■■■■■ □□□□□ ■ □□□ □□□□□ ■ □□□ □□□□□ ■ □□□ □□□□□ ■ □□□ □□□□□ ■ □□□ ↓ Select 6th from the top and 8th from the left □ ■ □□□ ■ □□□ ■■■■■■ □□□ □ ■ □□□ ■ □□□ ■■■■■■■■■ □□□□□ ■ □ ■ □ □□□□□ ■■■■ □□□□□ ■ □ ■ □ □□□□□ ■ □ ■ □ □□□□□ ■ □ ■ □

You want to create a grid where the color of the $i$ th cell from the top and the $j$ th cell from the left is $A_ {i, j}$. Find the minimum number of times to select a square.

Constraints

The input satisfies the following conditions.

• $3 \ le N \ le 127$
• $N$ is odd
• $A_ {i, j}$ is'o'or'x'
• Only input that can be made is given

Input

The input is given in the following format.

$N$ $A_ {1,1}$ $A_ {1,2}$ ... $A_ {1, N}$ $A_ {2,1}$ $A_ {2,2}$ ... $A_ {2, N}$ ... $A_ {N, 1}$ $A_ {N, 2}$ ... $A_ {N, N}$

When $A_ {i, j}$ is'o', it means that the $i$ th cell from the top and the $j$ th cell from the left are white, and when it is'x', it is a black cell. Represents that.

Output

Outputs the minimum number of times to select a cell on the first line.

Examples

Input

5 oxooo oxooo oxooo xxxxx oxooo

Output

1

Input

9 oxoooooxo oxxxxxxxx oxoooooxo xxxxxxxxx oxoxooooo oxxxxxxxx oxoxoxooo oxoxxxxxx oxoxoxooo

Output

4

inputFormat

input satisfies the following conditions.

• $3 \ le N \ le 127$
• $N$ is odd
• $A_ {i, j}$ is'o'or'x'
• Only input that can be made is given

Input

The input is given in the following format.

$N$ $A_ {1,1}$ $A_ {1,2}$ ... $A_ {1, N}$ $A_ {2,1}$ $A_ {2,2}$ ... $A_ {2, N}$ ... $A_ {N, 1}$ $A_ {N, 2}$ ... $A_ {N, N}$

When $A_ {i, j}$ is'o', it means that the $i$ th cell from the top and the $j$ th cell from the left are white, and when it is'x', it is a black cell. Represents that.

outputFormat

Output

Outputs the minimum number of times to select a cell on the first line.

Examples

Input

5 oxooo oxooo oxooo xxxxx oxooo

Output

1

Input

9 oxoooooxo oxxxxxxxx oxoooooxo xxxxxxxxx oxoxooooo oxxxxxxxx oxoxoxooo oxoxxxxxx oxoxoxooo

Output

4

样例

5
oxooo
oxooo
oxooo
xxxxx
oxooo

1