For this Question: We have N+M balls, each of which has an integer written on it.
It is known that:
 1) The numbers written on the N of the balls are even.
 2) The numbers written on the M of the balls are odd.
Find the number of ways to choose two of the N+M balls (disregarding order) so that the sum of the numbers written on them is even.The first and the only line of the input contains 2 space separated integers, N and M

<b>Constraints:</b>
1) 0 &le; N, M &le; 100
2) 2 &le; N + MPrint the answer<b>Sample Input 1:</b>
2 1

<b>Sample Output 1:</b>
1

<b>Sample Input 2:</b>
4 3

<b>Sample Output 2:</b>
9

<b>Sample Input 3:</b>
13 3

<b>Sample Output 3:</b>
81, I have written this Solution Code: #include <bits/stdc++.h>
using namespace std;
using ll = long long int;
using pii = pair<int,int>;
using vi = vector<int>;
using vll = vector<ll>;
using vvi = vector<vector<int>>;
using ss = string;
using db = double;
const int dx[4] = {1,0,-1,0};
const int dy[4] = {0,1,0,-1};
#define pi 3.14159265358979
#define rep(i,s,n) for(int i=(s);i<(int)(n);i++)
#define all(v) v.begin(),v.end()
#define ci(x) cin >> (x)
#define cii(x) int (x);cin >> (x)
#define cci(x,y) int (x),(y);cin >> (x) >>(y)
#define co(x) cout << (x) << endl

int main() {
  cci(n, m);
  co((n*(n-1))/2 + (m*(m-1))/2);
  return 0;
}, In this Programming Language: C++, Now tell me if this Code is compilable or not?