大佬们帮我看看，我这程序一直都编译失败，心态崩了呀！！！

#include<iostream>;
#include<cmath>
using namespace std; 
int main()
{
 int x1,y1,x2,y2,x3,y3,a,b,c,S,s;
 cin>>x1>>y1>>x2>>y2>>x3>>y3;
 a=sqrt((x1-x2)*(x1-x2)+(y1-Y2)*(y1-y2));
 b=sqrt((x1-x3)*(x1-x3)+(y1-y3)*(y1-y3));
 c=sqrt((x2-x3)*(x2-x3)+(y2-y3)*(y2-y3));
 s=(a+b+c)/2;
 S=sqrt((s-a)*(s-b)*(s-c));
 cout<<S;
 return 0;
}