program parkour;
const
    MAXN = 800;
    MAXM = 800;
var
    M, N, i,j : LongInt;
    level   : Array[0..MAXN-1,0..MAXM-1] of char;

begin
{
    uncomment the two following lines if you want to read/write from files
    assign(input,  'input.txt');  reset(input);
    assign(output, 'output.txt'); rewrite(output);
}

    ReadLn(N, M);

    for i := 0 to N-1 do 
                       for j:=0 to M-1 do level[i,j] := '.';
    if M<N then writeln(-1)
           else
              begin
                for i := 1 to N-1 do 
                        level[i,i-1] := '#';
                for i := 0 to N-1 do 
                     begin
                       for j:=0 to M-1 do write(level[i,j]);
                       writeln;
                     end;  
             end;        
end.