/* Template */

/*
 * Contest: AGC007
 * Author : shu
 * Date   : 2016/11/16
 */

/* Import */
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.util.InputMismatchException;

public class Main {
	public static final int A = 1;
	public static final int B = 2;
	public static final int C = 3;
	public static final int D = 4;
	public static final int E = 5;
	public static final int F = 6;

	public static final int PROBREM_NUMBER = A;

	public static void main(String[] args) {
		InputStream inputStream = System.in;
		OutputStream outputStream = System.out;
		InputReader in = new InputReader(inputStream);
		OutputWriter out = new OutputWriter(outputStream);
		Problem probrem = new Problem();
		probrem.solve(PROBREM_NUMBER, in, out);
		out.close();
	}
}

class Problem {
	public void solve(int probremNumber, InputReader in, OutputWriter out) {
		switch (probremNumber) {
		case Main.A:
			A(in, out);
			break;
		case Main.B:
			B(in, out);
			break;
		case Main.C:
			C(in, out);
			break;
		case Main.D:
			D(in, out);
			break;
		case Main.E:
			E(in, out);
			break;
		case Main.F:
			F(in, out);
			break;
		default:
			out.print("PROBREM SELECTION ERROR");
		}
	}

	public void A(InputReader in, OutputWriter out) {
		int h = in.nextInt();
		int w = in.nextInt();
		
		int[][] a = new int[h+2][w+2];
		boolean flag = true;
		int x = 1;
		int y = 1;
		
		for (int i=1; i<=h; i++) {
			for (int j=1; j<=w; j++) {
				if (in.readSkipSpace() == '#') {
					a[i][j] = 1;
				} else {
					a[i][j] = 0;
				}
			}
		}
		
		while (flag) {
			if (a[x+1][y] == 1) {
				if (a[x][y+1]==1 || a[x+1][y-1]==1) {
					flag = false;
				}
				x++;
			} else {
				if (a[x][y+1]==1) {
					if (a[x-1][y+1]==1) {
						flag = false;
					}
					y++;
				}
			}
			
			if (x==h && y==w && flag==true) {
				break;
			}
		}
		
		if (flag==true) {
			out.printLine("Possible");
		} else {
			out.printLine("Impossible");
		}
	}

	public void B(InputReader in, OutputWriter out) {

	}

	public void C(InputReader in, OutputWriter out) {

	}

	public void D(InputReader in, OutputWriter out) {

	}

	public void E(InputReader in, OutputWriter out) {

	}

	public void F(InputReader in, OutputWriter out) {

	}
}


class InputReader {
    private InputStream stream;
    private byte[] buffer = new byte[10000];
    private int cur;
    private int count;

    public InputReader(InputStream stream) {
        this.stream = stream;
    }

    public static boolean isSpace(int c) {
        return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
    }

    public int read() {
        if (count == -1) {
            throw new InputMismatchException();
        }
        try {
            if (cur >= count) {
                cur = 0;
                count = stream.read(buffer);
                if (count <= 0)
                    return -1;
            }
        } catch (IOException e) {
            throw new InputMismatchException();
        }
        return buffer[cur++];
    }

    public int readSkipSpace() {
        int c;
        do {
            c = read();
        } while (isSpace(c));
        return c;
    }

    public int nextInt() {
        int sgn = 1;
        int c = readSkipSpace();
        if (c == '-') {
            sgn = -1;
            c = read();
        }
        int res = 0;
        do {
            if (c < '0' || c > '9') {
                throw new InputMismatchException();
            }
            res = res * 10 + c - '0';
            c = read();
        } while (!isSpace(c));
        res *= sgn;
        return res;
    }

}

class OutputWriter {
    private final PrintWriter writer;

    public OutputWriter(OutputStream outputStream) {
        writer = new PrintWriter(new BufferedWriter(new OutputStreamWriter(outputStream)));
    }

    public void print(Object... objects) {
        for (int i = 0; i < objects.length; i++) {
            if (i != 0) {
                writer.print(' ');
            }
            writer.print(objects[i]);
        }
    }

    public void printLine(Object... objects) {
        print(objects);
        writer.println();
    }

    public void close() {
        writer.close();
    }
}

Measured memory_bytes: 8404