# Some special two variable function \$f(x, y)\$

I’m looking for a function $$f:mathbb{R}^2 rightarrow mathbb{R}$$ such that:

$$f(a, b) ge f(c, d) quadLongleftrightarrowquad a ge c text{and} b ge d$$

The origin of this problem is arisen from preferences theory in microeconomic.