import std.conv, std.functional, std.range, std.stdio, std.string;
import std.algorithm, std.array, std.bigint, std.bitmanip, std.complex, std.container, std.math, std.mathspecial, std.numeric, std.regex, std.typecons;
import core.bitop;

class EOFException : Throwable { this() { super("EOF"); } }
string[] tokens;
string readToken() { for (; tokens.empty; ) { if (stdin.eof) { throw new EOFException; } tokens = readln.split; } auto token = tokens.front; tokens.popFront; return token; }
int readInt() { return readToken.to!int; }
long readLong() { return readToken.to!long; }
real readReal() { return readToken.to!real; }

bool chmin(T)(ref T t, in T f) { if (t > f) { t = f; return true; } else { return false; } }
bool chmax(T)(ref T t, in T f) { if (t < f) { t = f; return true; } else { return false; } }

int binarySearch(alias pred, T)(in T[] as) { int lo = -1, hi = cast(int)(as.length); for (; lo + 1 < hi; ) { const mid = (lo + hi) >> 1; (unaryFun!pred(as[mid]) ? hi : lo) = mid; } return hi; }
int lowerBound(T)(in T[] as, T val) { return as.binarySearch!(a => (a >= val)); }
int upperBound(T)(in T[] as, T val) { return as.binarySearch!(a => (a > val)); }




void main() {
  try {
    for (; ; ) {
      const N = readLong();
      const K = readInt();
      auto A = new long[K];
      foreach (k; 0 .. K) {
        A[k] = readLong();
      }
      
      auto que = new RedBlackTree!long;
      foreach (k; 0 .. K) {
        que.insert(A[k]);
      }
      
      bool ans = true;
      long[] as;
      for (; !que.empty; ) {
        const a = que.back;
        que.removeBack;
        if (a == 1) {
          ans = false;
          break;
        }
        if (a <= 0) {
          break;
        }
        if (as.length >= 5) {
          bool hole = true;
          foreach (i; 1 .. 6) {
            hole = hole && (as[$ - i] == a + i);
          }
          if (hole) {
            ans = false;
            break;
          }
        }
        foreach (b; as) {
          if (a + 1 == b) que.insert(a - 3);
          if (a + 3 == b) que.insert(a - 2);
          if (a + 5 == b) que.insert(a - 1);
        }
        as ~= a;
      }
      
      writeln(ans ? "Yes" : "No");
    }
  } catch (EOFException e) {
  }
}