Bài 4:

program LN;
uses crt;
var A: array [1..10] of integer;
    n,i:integer;
begin
clrscr;
writeln('nhap n: ');
readln(n);
for i:= 1 to n do
        begin
        writeln('nhap vao ptu thu ',i,': ');
        readln(A[i]);
        end;
for i:= 1 to n do
        if A[i] < 0 then A[i]:=ABS(A[i]);
for i:= 1 to n do write(A[i],' ');
readln;
end.

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bài 2:

program LN;
uses crt;
var A: array [1..10] of integer;
    n,i,d,s:integer;
begin
clrscr;
s:=0;
writeln('nhap n: ');
readln(n);
for i:= 1 to n do
        begin
        writeln('nhap vao ptu thu ',i,': ');
        readln(A[i]);
        end;
for i:= 1 to n do
        if (A[i] mod 2 <> 0) and (A[i] < 45) then
                begin
                d:=d+1;
                s:=s+A[i];
                end;
writeln('co ',d,' ptu la so le va nho hon 45');
write('tong la : ',s);
readln;
end.