CONST
 m=4;
 n=5;
VAR
 B:ARRAY[1..m,1..n] of INTEGER;
 C,SUM:ARRAY[1..m] of INTEGER;
 Bul_1:ARRAY[1..n] of BOOLEAN;
 Bul_2:ARRAY[1..m] of BOOLEAN;
 i,j,p:INTEGER;
BEGIN
 Randomize;
 WriteLn('Initial matrix:');
 For i:=1 to m do
  begin
   for j:=1 to n do
    begin
     B[i,j]:=Random(100)-50;
     Write(B[i,j]:5);
    end;
   WriteLn;
  end;
 WriteLn;
 WriteLn('The prescribed vector:');
 For i:=1 to m do
  begin
   SUM[i]:=0;
   C[i]:=Random(10)-5;
   Write(C[i]:5);
  end;
 WriteLn;
 WriteLn('Press "Enter" to continue...');
 ReadLn;
 For j:=1 to n do
  Bul_1[j]:=false;
 For j:=1 to n do
  For i:=1 to m do
   If B[i,j]<0 then Bul_1[j]:=true;
 WriteLn('Reformed matrix:');
 For i:=1 to m do
  begin
   for j:=1 to n do
    begin
     If Bul_1[j] then B[i,j]:=C[i];
     Write(B[i,j]:5);
    end;
   WriteLn;
  end;
 WriteLn;
 WriteLn('Press "Enter" to continue...');
 ReadLn;
 For i:=1 to m do
  Bul_2[i]:=false;
 p:=0;
 For i:=1 to m do
  For j:=1 to n do
   If B[i,j]=0 then
    begin
     Bul_2[i]:=true;
     If (i mod 2)=0 then
      INC(p);
    end;
 For i:=1 to (m div 2) do
  If Bul_2[2*i] then
   begin
    for j:=1 to n do
     SUM[2*i]:=SUM[2*i]+B[2*i,j];
    WriteLn('SUM[',2*i,']= ',SUM[2*i]);
   end;
 If p=0 then
  WriteLn('There are no even strings, containing zero elements');
 ReadLn;
END.