#include<bits/stdc++.h>
#define pb emplace_back
#define AI(i) begin(i), end(i)
using namespace std;
using ll = long long;
template<class T>
bool chmax(T &val, T nv) { return val < nv ? (val = nv, true) : false; }
template<class T>
bool chmin(T &val, T nv) { return nv < val ? (val = nv, true) : false; }
#ifdef KEV
#define DE(args...) kout("[ " + string(#args) + " ] = ", args)
void kout() {cerr << endl;}
template<class T1, class ...T2>
void kout (T1 v, T2 ...e) { cerr << v << ' ', kout(e...); }
template<class T>
void debug(T L, T R) { while (L != R) cerr << *L << " \n"[next(L)==R], ++L; }
#else
#define DE(...) 0
#define debug(...) 0
#endif
// What I should check
// 1. overflow
// 2. corner cases
// Enjoy the problem instead of hurrying to AC
// Good luck !
/*
ID: ckevin31
LANG: C++14
TASK:
*/
#ifndef KEV
inline void IO(string name) {
    freopen((name + ".in").c_str(), "r", stdin);
    freopen((name + ".out").c_str(), "w", stdout);
}
#else
inline void IO(string name){}
#endif
int32_t main() {
    ios_base::sync_with_stdio(0), cin.tie(0);
    IO("gangs");
    int n, m;
    cin >> n >> m;
    vector<int> cnt(m), res;
    for (int &i : cnt) cin >> i;

    int mx = m == 1 ? 0 : *max_element(cnt.begin()+1, cnt.end());

    // x is answer, y is other 1s that we need to put in the front of the answer
    int x = min(cnt[0], n - mx * 2), y = cnt[0] - x;
    // if number of numbers other than one is odd, then we need to eliminate at least one with them
    if ((n - cnt[0]) % 2 == 1 && y == 0) ++y, --x;

    assert(x + y == cnt[0] && min(x, y) >= 0);

    if (x <= 0) return cout << "NO\n", 0;

    // Fid : The id of element in stack, Fcnt : The number of element in stack

    int Fid = 0, Fcnt = 0, sum = n - x;

    // We need the info of cur_max_element,
    // the number of elements left other than a bunch of ones
    vector<int> cntcnt(n + 1);
    for (int i = 1;i < m;++i) ++cntcnt[ cnt[i] ];
    int mxpointer = 1, cur_mx_cnt = n;

    auto put = [&](int id) {
        //cerr << "Put " << id+1 << endl;
        if (id == Fid || Fcnt == 0)
            ++Fcnt, Fid = id;
        else
            --Fcnt;
        if (id) {
            --cntcnt[ cnt[id]-- ], --sum;
            if (cnt[id] >= 0)
                ++cntcnt[ cnt[id] ];
        }
        res.pb(id);
    };

    auto get_most_freq = [&]() {
        while (cur_mx_cnt && cntcnt[ cur_mx_cnt ] == 0) --cur_mx_cnt;
        while (mxpointer < m && cnt[mxpointer] < cur_mx_cnt) ++mxpointer;
        return min(mxpointer, m - 1);
    };
    auto valid = [&](int put_id) {
        int g = get_most_freq();
        if (put_id == g || Fcnt == 0 || Fid != put_id) return true;
        return cnt[g] * 2 <= sum + Fcnt - 2;
    };

    for (int i = 0;i < y;++i) put(0);

    for (int i = 1;i < m;++i) {
        while (cnt[i]) {
            if (valid(i))
                put(i);
            else
                put(get_most_freq());
        }
    }

    for (int i = 0;i < x;++i) put(0);

    cout << "YES\n" << x << '\n';
    for (int u : res)
        cout << u+1 << '\n';
}