谁抄谁没浮木，也没78

include

using namespace std;

int main() {

int a, b, c, d, x, y;
cin >> a >> b >> c >> d;
x = a - c;
y = b - d;
if (x < 0) {
	x = x * -1;
} else {
	x = x;
}
if (y < 0) {
	y = y * -1;
} else {
	y = y;
}

cout << x + y;

return 0;

}