program calc;
uses crt;
var
x1, y1, x2, y2, x3, y3, a, b, c: real;
p, s: real;
Begin
writeln('Triangle');
write('Enter x1 and y1: ');
read(x1);
readln(y1);
write('Enter x2 and y2: ');
read(x2);
readln(y2);
write('Enter x3 and y3: ');
read(x3);
readln(y3);
a := sqrt(sqr(x1 - x2) + sqr(y1 - y2));
b := sqrt(sqr(x1 - x3) + sqr(y1 - y3));
c := sqrt(sqr(x3 - x2) + sqr(y3 - y2));
p := a + b + c;
writeln('P = ', p);
s := sqrt((p / 2) * (p / 2 - a) * (p / 2 - b) * (p / 2 - c));
writeln('S = ', s);
End.