求大神帮忙看看

#include<iostream>
#include<cstdio>
#include<cmath>
using namespace std;
int main(){
    double x1,y1,x2,y2,x3,y3,s1,s2,s3;
    cin>>x1>>y1>>x2>>y2>>x3>>y3;
    s1=sqrt((x3-x1)*(x3-x1)+(y3-y1)*(y3-y1));
    s2=sqrt((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2));
    s3=sqrt((x3-x2)*(x3-x2)+(y3-y2)*(y3-y2));
    double s=(s1+s2+s3)/2;
    cout<<int(sqrt(s*(s-s1)*(s-s2)*(s-s3)));
    return 0;
}