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