a = sqrt((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2));
b = sqrt((x3-x2)*(x3-x2)+(y3-y2)*(y3-y2));
c = sqrt((x1-x3)*(x1-x3)+(y1-y3)*(y1-y3));
writeln("Периметр = ",a+b+c);
s = {Формула герона}
a = sqrt((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2));
b = sqrt((x3-x2)*(x3-x2)+(y3-y2)*(y3-y2));
c = sqrt((x1-x3)*(x1-x3)+(y1-y3)*(y1-y3));
writeln("Периметр = ",a+b+c);
s = {Формула герона}