#pragma GCC optimize("Ofast")

#include <bits/stdc++.h>

#define LL long long int
#define ULL unsigned LL
#define LD long double
#define FI first
#define SE second
#define PB push_back
#define PF push_front
#define V vector
#define PQ priority_queue
#define ALL(x) x.begin(), x.end()
#define SZ(x) (int)(x).size()
#define FORI(i, a, b) for(int i = a; i < b ; ++i)
#define FORD(i, a, b) for(int i = a; i > b ; --i)

using namespace std;
using pii = pair<int, int>;

const int INF = 1e9;

void fill(int segment, int& pos, int& val, int& jumps, int p, V<int>& a){
    FORI(_,0,segment){
        a[pos++] = val--;
        if (val == 1){
            val = p;
            jumps++;
        }
    }
}

int main(){
    ifstream cin("notdecreasing.in");
    ofstream cout("notdecreasing.out");
    mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
    clock_t start_t = clock();

    int n, p, l = 0;
    cin >> n >> p;
    V<int> b(n), segs;
    bool imp = 0;
    FORI(r,0,n){
        cin >> b[r];
        if (r){
            if (b[r-1] > b[r]){
                imp = 1;
                break;
            }
            if (b[r-1] < b[r]){
                segs.push_back(r - l + 1);
                l = r + 1;
            }
        }
    }
    imp |= b[n-1] == 0;
    if (imp){
        cout << -1;
        return 0;
    }
//    for(auto seg: segs){
//        cout << seg << ' ';
//    }
    int pos = 0, val = p, jumps = 0;
    V<int> a(n);
    for(auto seg: segs){
        fill(seg-1, pos, val, jumps, p, a);
        if (jumps-- == 0){
            cout << -1;
            return 0;
        }
        a[pos++] = 1;
    }
    fill(n-pos, pos, val, jumps, p, a);
    l = 0;
    FORI(r,0,n){
        if (a[r] == 1){
            sort(a.begin()+l, a.begin()+r, greater<int>());
            l = r + 1;
        }
    }
    sort(a.begin()+l, a.end(), greater<int>());
    FORI(i,0,n){
        cout << a[i] << ' ';
    }

    return 0;
}