#include <bits/stdc++.h>
#define endl '\n'
using namespace std;

const int MAXN = 1e5+5;
const int INF = 2e9;
int n, p;
int b[MAXN];
int a[MAXN];
int cnt[MAXN];

int tree[4 * MAXN];

void update(int L, int R, int node, int ind)
{
    if (ind < L || ind > R) return;
    if (L == R)
    {
        if (tree[node] == INF) tree[node] = 1;
        tree[node] += 1;
        return;
    }
    int mid = (L + R) / 2;

    update(L, mid, node * 2, ind);
    update(mid + 1, R, node * 2 + 1, ind);

    tree[node] = min(tree[node * 2], tree[node * 2 + 1]);
}

int main()
{
    freopen("notdecreasing.in", "r", stdin);
    freopen("notdecreasing.out", "w", stdout);

    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);

    cin >> n >> p;
    for (int i = 1; i <= n; i++)
        cin >> b[i];

    int prev = p;

    for (int i = 1; i <= n; i++)
    {
        if (cnt[1] < b[i])
        {
            a[i] = 1;
            cnt[1]++;
        }
        else
        {
            a[i] = prev;
            cnt[prev]++;

            prev--;
            if (prev == 1) prev = p;
        }
    }

    for (int i = 1; i <= n; i++)
    {
        update(1, p, 1, a[i]);

        if (tree[1] != b[i])
        {
            cout << -1 << endl;
            return 0;
        }
    }

    for (int i = 1; i <= n; i++)
        cout << a[i] << " ";
    cout << endl;

    return 0;
}
/**

4 2
0 1 1 2



*/