My First C++ Program

#include <iostream>
#include <string>
#include <cmath>
using namespace std;
int main() {

int x;
int y;
int r;
string greeting = "Hello I am your new calculator please ";
cout << greeting;
  cout << "type a number: ";
  cin >> x;
  cout << "another number please " ;
  cin >> y;
  cout << "1 more number please." ;
  cin >> r ;
  cout << "answer is :" <<x+y-r;
  return 0;
}

I created a basic calculator that could determine a+b-c when numbers were inputted. This was made in late 2019, I was five years old.