- initialize L3 to be equal to L1 (a copy of L1).
- for each element E in L2, INSERT E (a copy of E) into L3.

To illustrate this algorithm consider the earlier example: L1 = [11,99] and L2 = [2,111,222].

- L3 = [11,99]
- INSERT 2 into L3. Compare 2 to 11; it's smaller so 2 goes before
11, i.e. at the very beginning of L3. Result: L3 = [2,11,99].
INSERT 111 into L3. Compare 111 to 2. It's bigger, so compare 111 to the next element. 111 > 11, so compare 111 to the next element. 111 > 99 and 99 is the last element in L3, so add 111 after 99. Result: L3 = [2,11,99,111].

INSERT 222 into L3. Compare 222 to 2. It's bigger so compare 222 to the next element. 222 > 11, so compare it to the next element. 222 > 99, so compare it to the next element. 222 > 111 and 111 is the last element, so add 222 after 111. Result: L3 = [2,11,99,111,222].