feat(sum.cpp): implemented sum and probably overcomplicated it

exercises/sum.cpp

@@ -6,3 +6,29 @@
   Insert the second number: 2
   Sum: 3
 */
+#include <iostream>
+using namespace std;
+
+#define EXIT_SUCCESS 0
+#define EXIT_FAILURE 1
+
+void getNumInput(int* num);
+template <typename T> void printSum(const T& n1, const T& n2);
+
+void getNumInput(int* num){
+  cout << "Insert the first number: " << endl;
+  cin >> num[0];
+  cout << "Insert the second number: " << endl;
+  cin >> num[1];
+}
+
+template <typename T> void printSum(const T& n1, const T& n2){
+  cout << "Sum: " << n1 + n2 << endl;
+}
+
+int main(){
+  int number[2];
+  getNumInput(number);
+  printSum<int>( number[0] , number[1] );
+  return EXIT_SUCCESS;
+}