uses crt;
const fi='bai1.inp'
var f1:text;
a,b,c,cv,dt,p:real;
begin
clrscr;
assign(f1,fi); rewrite(f1);
write('Nhap a='); readln(a);
write('Nhap b='); readln(b);
write('Nhap c='); readln(c);
if (a>0) and (b>0) and (c>0) and (a+b>c) and (a+c>b) and (b+c>a) then
begin
cv:=a+b+c;
p:=cv/2;
dt:=sqrt(p*(p-a)*(p-b)*(p-c));
writeln(f1,'Chu vi la: ',cv:4:2);
writeln(f1,'Dien tich la: ',dt:4:2);
end
else writeln(f1,'Day khong la ba canh trong mot tam giac');
close(f1);
readln;
end.