Program C++ (menghitung luas segitiga)

#include<iostream.h>
int luas_s (int a, int t)
main ()
{

int ls,as,ts;
cin>>as;
cin>>ts;
ls=luas_s (int a,int t);
cout<<ls;
}
int luas_s(int a, int t)
{
int l;
l = 1/2 * a * t;
return l;
}
silahkan dicoba ^_^