$\left\{\left(0,4\right),\left(1,2\right),\left(2,3\right),\left(4,9\right),\left(1,3\right)\right\}$

$\left\{\left(19,0\right),\left(1,10\right),\left(9,0\right),\left(20,8\right)\right\}$

$\left\{\left(x,4\right),\left(y,4\right),\left(x,2\right)\right\}$

$\left\{\left(A,1\right),\left(B,15\right),\left(D,10\right),\left(C,2\right),\left(E\right),\left(F,4\right)\right\}$

$\left\{\left(A,1\right),\left(B,1\right),\left(B,4\right),\left(A,5\right)\right\}$