#include<bits/stdc++.h>
using namespace std;
using LL = long long;
using ULL = unsigned long long;
#define rep(i,n) for(int i=0; i<(n); i++)

ULL N;
int K;
ULL A[100];
bool G[2000] = {};

int main() {
    cin >> N >> K;
    rep(i, K) { cin >> A[i]; A[i]--; }
    rep(i, K - 1) { if (A[i] >= 500) if (A[i] + 6 > A[i + 1]) { cout << "No" << endl; return 0; } }

    rep(i, K) if (A[i] < 1000) G[A[i]] = true;

    for (int i = 999; i >= 0; i--) {
        if (G[i + 1] && G[i + 6]) G[i] = true;
        if (G[i + 2] && G[i + 5]) G[i] = true;
        if (G[i + 3] && G[i + 4]) G[i] = true;
    }

    cout << (G[0] ? "No" : "Yes") << endl;

    return 0;
}