clrscr;
write('nhap canh a: ');readln(a);
P:=a*4;
S:=a*a;
writeln('Chu vi hinh vuong canh a la: ',P);
writeln('Dien tich hinh vuong canh a la: ',S);
uses crt;
var a,cv,dt:real;
begin
clrscr;
repeat
write('Nhap a='); readln(a);
until a>0;
cv:=a*4;
dt:=sqr(a);
writeln('Chu vi la: ',cv:4:2);
writeln('Dien tich la: ',dt:4:2);
readln;
end.