Problem: We have a grid of H rows and W columns. Initially, there is a stone in the top left cell. Shik is trying to move the stone to the bottom right cell. In each step, he can move the stone one cell to its left, up, right, or down (if such cell exists). It is possible that the stone visits a cell multiple times (including the bottom right and the top left cell).

You are given a matrix of characters a_{ij} (1 \leq i \leq H, 1 \leq j \leq W). After Shik completes all moving actions, a_{ij} is `#` if the stone had ever located at the i-th row and the j-th column during the process of moving. Otherwise, a_{ij} is `.`. Please determine whether it is possible that Shik only uses right and down moves in all steps.

Constraints

* 2 \leq H, W \leq 8
* a_{i,j} is either `#` or `.`.
* There exists a valid sequence of moves for Shik to generate the map a.

Input

The input is given from Standard Input in the following format:


H W
a_{11}a_{12}...a_{1W}
:
a_{H1}a_{H2}...a_{HW}


Output

If it is possible that Shik only uses right and down moves, print `Possible`. Otherwise, print `Impossible`.

Examples

Input

4 5
##...
.##..
..##.
...##


Output

Possible


Input

4 5
...
.##..
..##.
...##


Output

Possible


Input

5 3

..#

..


Output

Impossible


Input

4 5
...
.###.
.###.
...##


Output

Impossible

Solution (in JAVA):

Solution:

import java.util.Arrays;
import java.util.Scanner;

public class Main {
    MyScanner sc    = new MyScanner();
    Scanner   sc2   = new Scanner(System.in);
    long      start = System.currentTimeMillis();
    long      fin   = System.currentTimeMillis();
    final int MOD   = 1000000007;
    int[]     dx    = { 1, 0, 0, -1 };
    int[]     dy    = { 0, 1, -1, 0 };

    int       H, W;
    char[][]  f;
    int[][]   c;
    boolean   ok, g;

    void run() {
        H = sc.nextInt();
        W = sc.nextInt();
        f = sc.nextCharField(H, W);
        c = new int[H][W];
        ok = true;
        g = false;
        for (int i = 0; i < H; i++) {
            for (int j = 0; j < W; j++) {
                if (f[i][j] == '#') {
                    c[i][j] = 1;
                }
            }
        }
        dfs(0, 0);
        for (int i = 0; i < H; i++) {
            for (int j = 0; j < W; j++) {
                if (c[i][j] == 1)
                    ok = false;
            }
        }
        System.out.println(ok ? "Possible" : "Impossible");
    }

    void dfs(int nh, int nw) {
        if(g) return;
        if (inner(nh - 1, nw, H, W) && inner(nh, nw - 1, H, W)) {
            if (f[nh - 1][nw] == '#' && f[nh][nw - 1] == '#') {
                ok = false;
            }
        }

        c[nh][nw] = 2;
        if (nh == H - 1 && nw == W - 1) {
            g = true;
            return;
        }
        if (inner(nh + 1, nw, H, W) && f[nh + 1][nw] == '#') {
            dfs(nh + 1, nw);
            if(!g) c[nh + 1][nw] = 1;
        }
        if (inner(nh, nw + 1, H, W) && f[nh][nw + 1] == '#') {
            dfs(nh, nw + 1);
            if(!g) c[nh ][nw + 1] = 1;
        }
    }

    public static void main(String[] args) {
        new Main().run();
    }

    void debug(Object... o) {
        System.out.println(Arrays.deepToString(o));
    }

    void debug2(int[][] array) {
        for (int i = 0; i < array.length; i++) {
            for (int j = 0; j < array[i].length; j++) {
                System.out.print(array[i][j]);
            }
            System.out.println();
        }
    }

    boolean inner(int h, int w, int limH, int limW) {
        return 0 <= h && h < limH && 0 <= w && w < limW;
    }

    void swap(int[] x, int a, int b) {
        int tmp = x[a];
        x[a] = x[b];
        x[b] = tmp;
    }

    // find minimum i (k <= a[i])
    int lower_bound(int a[], int k) {
        int l = -1;
        int r = a.length;
        while (r - l > 1) {
            int mid = (l + r) / 2;
            if (k <= a[mid])
                r = mid;
            else
                l = mid;
        }
        // r = l + 1
        return r;
    }

    // find minimum i (k < a[i])
    int upper_bound(int a[], int k) {
        int l = -1;
        int r = a.length;
        while (r - l > 1) {
            int mid = (l + r) / 2;
            if (k < a[mid])
                r = mid;
            else
                l = mid;
        }
        // r = l + 1
        return r;
    }

    int gcd(int a, int b) {
        return a % b == 0 ? b : gcd(b, a % b);
    }

    int lcm(int a, int b) {
        return a * b / gcd(a, b);
    }

    boolean palindrome(String s) {
        for (int i = 0; i < s.length() / 2; i++) {
            if (s.charAt(i) != s.charAt(s.length() - 1 - i)) {
                return false;
            }
        }
        return true;
    }

    class MyScanner {
        int nextInt() {
            try {
                int c = System.in.read();
                while (c != '-' && (c < '0' || '9' < c))
                    c = System.in.read();
                if (c == '-')
                    return -nextInt();
                int res = 0;
                do {
                    res *= 10;
                    res += c - '0';
                    c = System.in.read();
                } while ('0' <= c && c <= '9');
                return res;
            } catch (Exception e) {
                return -1;
            }
        }

        double nextDouble() {
            return Double.parseDouble(next());
        }

        long nextLong() {
            return Long.parseLong(next());
        }

        String next() {
            try {
                StringBuilder res = new StringBuilder("");
                int c = System.in.read();
                while (Character.isWhitespace(c))
                    c = System.in.read();
                do {
                    res.append((char) c);
                } while (!Character.isWhitespace(c = System.in.read()));
                return res.toString();
            } catch (Exception e) {
                return null;
            }
        }

        int[] nextIntArray(int n) {
            int[] in = new int[n];
            for (int i = 0; i < n; i++) {
                in[i] = nextInt();
            }
            return in;
        }

        int[][] nextInt2dArray(int n, int m) {
            int[][] in = new int[n][m];
            for (int i = 0; i < n; i++) {
                in[i] = nextIntArray(m);
            }
            return in;
        }

        double[] nextDoubleArray(int n) {
            double[] in = new double[n];
            for (int i = 0; i < n; i++) {
                in[i] = nextDouble();
            }
            return in;
        }

        long[] nextLongArray(int n) {
            long[] in = new long[n];
            for (int i = 0; i < n; i++) {
                in[i] = nextLong();
            }
            return in;
        }

        char[][] nextCharField(int n, int m) {
            char[][] in = new char[n][m];
            for (int i = 0; i < n; i++) {
                String s = sc.next();
                for (int j = 0; j < m; j++) {
                    in[i][j] = s.charAt(j);
                }
            }
            return in;
        }
    }
}