#include <bits/stdc++.h>
using namespace std;
using LL = long long int;
#define incII(i, l, r) for(LL i = (l)    ; i <= (r); i++)
#define incIX(i, l, r) for(LL i = (l)    ; i <  (r); i++)
#define incXI(i, l, r) for(LL i = (l) + 1; i <= (r); i++)
#define incXX(i, l, r) for(LL i = (l) + 1; i <  (r); i++)
#define decII(i, l, r) for(LL i = (r)    ; i >= (l); i--)
#define decIX(i, l, r) for(LL i = (r) - 1; i >= (l); i--)
#define decXI(i, l, r) for(LL i = (r)    ; i >  (l); i--)
#define decXX(i, l, r) for(LL i = (r) - 1; i >  (l); i--)
#define inc(i, n)  incIX(i, 0, n)
#define dec(i, n)  decIX(i, 0, n)
#define inc1(i, n) incII(i, 1, n)
#define dec1(i, n) decII(i, 1, n)
auto inII = [](auto x, auto l, auto r) { return (l <= x && x <= r); };
auto inIX = [](auto x, auto l, auto r) { return (l <= x && x <  r); };
auto inXI = [](auto x, auto l, auto r) { return (l <  x && x <= r); };
auto inXX = [](auto x, auto l, auto r) { return (l <  x && x <  r); };
auto setmin   = [](auto & a, auto b) { return (b <  a ? a = b, true : false); };
auto setmax   = [](auto & a, auto b) { return (b >  a ? a = b, true : false); };
auto setmineq = [](auto & a, auto b) { return (b <= a ? a = b, true : false); };
auto setmaxeq = [](auto & a, auto b) { return (b >= a ? a = b, true : false); };
#define PB push_back
#define EB emplace_back
#define MP make_pair
#define MT make_tuple
#define FI first
#define SE second
#define FR front()
#define BA back()
#define ALL(c) c.begin(), c.end()
#define RALL(c) c.rbegin(), c.rend()
#define RV(c) reverse(ALL(c))
#define SC static_cast
#define SI(c) SC<int>(c.size())
#define SL(c) SC<LL >(c.size())
#define RF(e, c) for(auto & e: c)
#define SF(c, ...) for(auto & [__VA_ARGS__]: c)
#define until(e) while(! (e))
#define if_not(e) if(! (e))
#define ef else if
#define UR assert(false)
auto * IS = & cin;
auto * OS = & cout;
array<string, 3> SEQ = { "", " ", "" };
// input
template<typename T> T in() { T a; (* IS) >> a; return a; }
// input: tuple
template<int I, typename U> void tin_(istream & is, U & t) {
	if constexpr(I < tuple_size<U>::value) { is >> get<I>(t); tin_<I + 1>(is, t); }
}
template<typename ... T> istream & operator>>(istream & is, tuple<T ...> & t) { tin_<0>(is, t); return is; }
template<typename ... T> auto tin() { return in<tuple<T ...>>(); }
// input: array
template<typename T, size_t N> istream & operator>>(istream & is, array<T, N> & a) { RF(e, a) { is >> e; } return is; }
template<typename T, size_t N> auto ain() { return in<array<T, N>>(); }
// input: multi-dimensional vector
template<typename T> T vin() { T v; (* IS) >> v; return v; }
template<typename T, typename N, typename ... M> auto vin(N n, M ... m) {
	vector<decltype(vin<T, M ...>(m ...))> v(n); inc(i, n) { v[i] = vin<T, M ...>(m ...); } return v;
}
// input: multi-column (tuple<vector>)
template<typename U, int I> void colin_([[maybe_unused]] U & t) { }
template<typename U, int I, typename A, typename ... B> void colin_(U & t) {
	get<I>(t).PB(in<A>()); colin_<U, I + 1, B ...>(t);
}
template<typename ... T> auto colin(int n) {
	tuple<vector<T> ...> t; inc(i, n) { colin_<tuple<vector<T> ...>, 0, T ...>(t); } return t;
}
// output
void out_([[maybe_unused]] string s) { }
template<typename A> void out_([[maybe_unused]] string s, A && a) { (* OS) << a; }
template<typename A, typename ... B> void out_(string s, A && a, B && ... b) { (* OS) << a << s; out_(s, b ...); }
auto outF = [](auto x, auto y, auto z, auto ... a) { (* OS) << x; out_(y, a ...); (* OS) << z << flush; };
auto out  = [](auto ... a) { outF("", " " , "\n", a ...); };
auto outS = [](auto ... a) { outF("", " " , " " , a ...); };
auto outL = [](auto ... a) { outF("", "\n", "\n", a ...); };
auto outN = [](auto ... a) { outF("", ""  , ""  , a ...); };
// output: multi-dimensional vector
template<typename T> ostream & operator<<(ostream & os, vector<T> const & v) {
	os << SEQ[0]; inc(i, SI(v)) { os << (i == 0 ? "" : SEQ[1]) << v[i]; } return (os << SEQ[2]);
}
template<typename T> void vout_(T && v) { (* OS) << v; }
template<typename T, typename A, typename ... B> void vout_(T && v, A a, B ... b) {
	inc(i, SI(v)) { (* OS) << (i == 0 ? "" : a); vout_(v[i], b ...); }
}
template<typename T, typename A, typename ... B> void vout (T && v, A a, B ... b) { vout_(v, a, b ...); (* OS) << a << flush; }
template<typename T, typename A, typename ... B> void voutN(T && v, A a, B ... b) { vout_(v, a, b ...); (* OS)      << flush; }

// ---- ----

int main() {
	auto f = [](int p) -> set<LL> {
		set<int> se;
		auto c = [&](int i) -> bool { return (se.count(i) == 1); };
		
		se.insert(0);
		se.insert(p);
		for(int i = 0; true; i++) {
			bool g = true;
			inc(j, 6) { g &= c(i + j); }
			if(g) {
				set<LL> ans;
				inc(j, i) { if_not(c(j)) { ans.insert(j); } }
				return ans;
			}
			
			if(c(i) && c(i + 1)) { se.insert(i + 4); }
			if(c(i) && c(i + 3)) { se.insert(i + 5); }
			if(c(i) && c(i + 5)) { se.insert(i + 6); }
		}
		UR;
	};
	auto no  = []() { out("No");  exit(0); };
	auto yes = []() { out("Yes"); exit(0); };
	
	array<set<LL>, 3> S;
	inc(i, 3) { S[i] = f(2 * i + 1); }
	
	auto [n, k] = tin<LL, int>();
	auto a = vin<LL>(k);
	
	int p = 0;
	dec(i, k - 1) {
		LL d = a[i + 1] - a[i];
		if(d < 6 && d % 2 == 1) {
			setmax(p, i + 1);
			if(S[d / 2].count(a[i + 1] - 1) == 0) { no(); }
		}
	}
	if(p == 0) { yes(); }
	
	until(SI(a) <= p + 1) { a.pop_back(); }
	set<LL> x;
	RF(e, a) { x.insert(e); }
	auto c = [&](LL v) -> bool { return (x.count(v) == 1); };
	
	dec(i, a.BA + 1) {
		if(c(i) && c(i - 1)) { x.insert(i - 4); }
		if(c(i) && c(i - 3)) { x.insert(i - 5); }
		if(c(i) && c(i - 5)) { x.insert(i - 6); }
	}
	c(1) ? no() : yes();
}