Не могу найти ошибки в программах

program opfor;
uses crt;
var ak,bk,b1,p:real;
k:integer;
begin
clrscr;
b1:=0.01;
p:=1;
for k:= to 6 do begin
ak:=sqr(sin(3*k+5))-cos(sqr(k)-15);
bk:=sin(k+bk-b1);
p:=p*((1+ak)/(1+bk)+sqrt(ak+bk));
end;
writeln ('P=', p:5:2);
readkey;
end.

program mass1;
uses crt;
var y,z:array [1..10] of read;
i,k:integer;
s,max:real;
begin
clrscr;
writeln ('Enter array Y');
k:=0;
for i:=1 to 10 do read (y[i]);
if (y[i]>0) and (y[i]<=15) then
begin
k:=k+1;
z[k]:=y[i]
end
else
begin
k:=k+1;
z[k]:=2.7
end;
writeln ('Array Z:');
for k:=1 to 10 do wtiteln (z[k]:4:2);
s:=0;
for i:=1 to 10 do
s:=s+sqr(sqrt(z[i])-z[i]);
max:=y[1];
for i:=2 to 10 do
if y[i]>max then max:=y[i];
writeln ('S=', s:4:2);
writeln ('Max Y=', max:4:2);
readkey;
end.

for k:=1 to 6 do begin

program opfor;
uses crt;
const n=6;
var a,b:array[1..n] of real;
    p:real;
    k:integer;
begin
clrscr;
b[1]:=0.01;
for k:=1 to 6 do
begin
a[k]:=sqr(sin(3*k+5))-cos(sqr(k)-15);
write(a[k]:0:2,' ');
end;
writeln;
for k:=2 to n do
b[k]:=sin(k+b[k-1]);
for k:=1 to n do
write(b[k]:0:2,' ');
{p:=1;
for k:=1 to n do
p:=p*((1+a[k])/(1+b[k])+sqrt(a[k]+b[k]));
writeln ('P=', p:5:2); }
readkey;
end.

program opfor;
uses crt;
const n=10;
var y,z:array[1..n] of real;
    s,mx:real;
    i:integer;
begin
clrscr;
writeln('Введите ',n,' элементов массива:');
for i:=1 to n do
 begin
  write('y[',i,']=');
  readln(y[i]);
 end;
clrscr;
mx:=y[1];
writeln('Массив Y:');
for i:=1 to n do
 begin
   write(y[i]:0:2,' ');
   if y[i]>mx then mx:=y[i];
 end;
writeln;
writeln('Максимальный=',mx:0:2);
writeln;
writeln('Массив Z:');
for i:=1 to n do
 begin
  if(y[i]>0)and(y[i]<15) then z[i]:=y[i]
  else z[i]:=2.7;
  write(z[i]:0:2,' ');
 end;
readkey
end.