This program illustrates the use of the STL set_union() algorithm (extended version) to find the values that are in a first vector of integers or in a second vector of integers (or in both), and write them out to a third vector of integers. In this case the vectors are ordered in the sense that one integer comes before another if and only if it has a smaller digit sum. Press Enter to continue ... Here are the values in the vector v1: 11 12 12 12 12 13 14 15 Press Enter to continue ... Here are the values in the vector v2: 2 21 21 31 31 61 71 81 Press Enter to continue ... Here are the values in the vector v3: 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 Press Enter to continue ... Now we find the values that are in v1 or in v2, or in both, and write them out to v3, starting at the beginning of v3. Press Enter to continue ... Here are the revised contents of v3: 11 12 12 12 12 13 31 14 15 61 71 81 113 114 115 Press Enter to continue ... The iterator returned by the algorithm is pointing at the value 113. Press Enter to continue ...