import java.util.Scanner;
class Main
{
{
Scanner input
= new Scanner
(System.
in); int[] a = new int[4];
for (int i = 0; i < 4; i++) {
a[i] = input.nextInt();
}
input.close();
System.
out.
println(a
[0]*a
[1]+a
[2]*a
[3]); }
}
aW1wb3J0IGphdmEudXRpbC5TY2FubmVyOwoKY2xhc3MgTWFpbgp7CglwdWJsaWMgc3RhdGljIHZvaWQgbWFpbiAoU3RyaW5nW10gYXJncykgdGhyb3dzIGphdmEubGFuZy5FeGNlcHRpb24KCXsKCQlTY2FubmVyIGlucHV0ID0gbmV3IFNjYW5uZXIoU3lzdGVtLmluKTsKCQlpbnRbXSBhID0gbmV3IGludFs0XTsKCQlmb3IgKGludCBpID0gMDsgaSA8IDQ7IGkrKykgewoJCQlhW2ldID0gaW5wdXQubmV4dEludCgpOwoJCX0KCQlpbnB1dC5jbG9zZSgpOwoJCVN5c3RlbS5vdXQucHJpbnRsbihhWzBdKmFbMV0rYVsyXSphWzNdKTsgCgl9Cn0=