#include <iostream>
using namespace std;
signed main() {
int a, b, c, AC, BC;
cin >> a >> b >> c;
AC = c - a;
BC = b - c;
cout << AC * BC << endl;
return 0;
}
#include <iostream>
using namespace std;
signed main() {
int a, b, c, AC, BC;
cin >> a >> b >> c;
AC = c - a;
BC = b - c;
cout << AC * BC << endl;
return 0;
}