#include<bits/stdc++.h>

using namespace std;

struct Str
{
    int i0, i1, i2;
    Str(int _i0, int _i1, int _i2)
    {
        i0 = _i0;
        i1 = _i1;
        i2 = _i2;
    }
};

struct My
{
    int i1, i2;
    My(int _i1, int _i2)
    {
        i1 = _i1;
        i2 = _i2;
    }
};

bool cmp2(Str a, Str b)
{
    if(a.i0 != b.i0)
        return a.i0 < b.i0;
    else if(a.i1 != b.i1)
        return a.i1 < b.i1;
    else
        return a.i2 < b.i2;
}

bool cmp1(My a, My b)
{
    if(a.i1 != b.i1)
        return a.i1 < b.i1;
    else
        return a.i2 < b.i2;
}

int main()
{
    int n, m;
    cin >> n >> m;
    vector<int> ans(m + 1);
    set<My, decltype(&cmp1)> s1(cmp1);
    s1.insert({-n, 1});
    set<Str, decltype(&cmp2)> s2(cmp2);
    s2.insert(Str(1, n, 0));
    for(int i = 1; i <= m; i++)
    {
        int value;
        cin >> value;
        if(value > 0)
        {
            auto c =* s1.begin();
            c.i1 = -c.i1;
            if(c.i1 < value)
            {
                ans[i] = -1;
                cout <<- 1 << endl;
                continue;
            }
            ans[i] = c.i2;
            cout << c.i2 << endl;
            c.i1 = -c.i1;
            s1.erase(c);
            c.i1 = -c.i1;
            s2.erase(Str(c.i2, c.i1, 0));
            s2.insert(Str(c.i2, value, 1));
            if(c.i1 - value > 0)
            {
                int nw_len = c.i1 - value, l = c.i2 + value;
                s1.insert({-nw_len, l});
                s2.insert(Str(l, nw_len, 0));
            }
        }
        else
        {
            if(ans[ - value] == -1)
                continue;
            auto c = s2.lower_bound(Str(ans[ - value], -1, -1));
            int l, _size, fl;
//          Str(l, _size, fl) = *c;
            l = (c -> i0);
            _size = (c -> i1);
            fl = (c -> i2);
            auto node = s2.end();
            -- node;
            if(c != node)
            {
                ++ c;
                if(!(c -> i2))
                {
                    _size += (c -> i1);
                    s2.erase(c);
                    s1.erase({-(c -> i1), (c -> i0)});
                }
                c = s2.lower_bound(Str(ans[ - value], -1, -1));
            }
            if(c != s2.begin())
            {
                -- c;
                if(!(c -> i2))
                {
                    l = (c -> i0);
                    _size += (c -> i1);
                    s2.erase(c);
                    s1.erase({-(c -> i1), (c -> i0)});
                }
                c = s2.lower_bound(Str(ans[-value], -1, -1));
            }
            s2.erase(c);
            s2.insert(Str(l, _size, 0));
            s1.insert({-_size, l});
        }
    }
}