#include <bits/stdc++.h>
using namespace std;
int main() {
  int a, b, c, x, y, z;
  cin >> a >> b >> c;
  cin >> x >> y >> z;
  a = a - x;
  b = b - y;
  c = c - z;
  if (a > 0) a = a / 2;
  if (b > 0) b = b / 2;
  if (c > 0) c = c / 2;
  if ((a + b + c) >= 0)
    cout << "YES" << endl;
  else
    cout << "NO" << endl;
  return 0;
}
