# Surrounded Islands

You are given a two-dimensional integer matrix `matrix`

containing `1`

s and `0`

s. `1`

represents land and `0`

represents water. An island is a group of 1s that are neighboring whose perimeter is surrounded by water. Return the number of completely surrounded islands.

**Constraints**

`n, m ≤ 250`

where`n`

and`m`

are the number of rows and columns in`matrix`

.

https://binarysearch.com/problems/Surrounded-Islands

## Examples

### Example 1

**Input**

- matrix =

```
[[1,1,0,0,0],
[0,0,0,0,0],
[0,1,1,1,0],
[0,1,0,1,0],
[0,1,1,1,0],
[0,0,0,0,0]]
```

**Output**

- answer =
`1`

**Explanation**

There’s `2`

islands but only the middle island is completely surrounded.

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