#include <iostream>
#include <string>
#include <set>
#include <map>
#include <algorithm>
#include <iomanip>
#include <vector>
#include <cmath>
#include <queue>
#include <sstream>
#include <ctime>
#include <iterator>
#include <string.h>
#include <stack>
#include <unordered_set>
#include <unordered_map>
#include <bitset>
#include <fstream>
#include <assert.h>
#include <numeric>
#include <complex>
#include <random>
#include <utility>



#define IOS ios_base::sync_with_stdio(0),cin.tie(0), cout.tie(0);
#define FOR(i,a,b) for(int i = (a); i < (b); i++)
#define RFOR(i,a,b) for(int i = (a) - 1; i>=(b);i--)
#define rep(i,n) FOR(i,0,n)
#define PB push_back
#define SZ(a) (int)a.size()
#define ALL(a) a.begin(), a.end()
#define VI vector<int>
#define PII pair<int,int>
#define PLL pair<long long,long long>
#define VL vector<long long >
#define FILL(a, value) memset(a, value, sizeof(a))
const int nax = 2 * (int)1e5 + 147;
 
using namespace std;
 
const int MOD = 998244353;
const int INF = 1e9 +47 ;
const long long LINF = (long long)1e18 + 4747;
 
typedef long long LL;
const double EPS=1e-6;

int main() {
    int n, q;
        cin >> n >> q;
        set<int >s ;
        FOR (i, 0, q)
        {
            char c;
            int a, b;
            cin >> c >> a;
            if (c == '+')
                s.erase(a);
            else if (c == '-')
                s.insert(a);
            else
            {
                cin >> b;
                if (SZ(s) < 2)
                {
                    cout << "possible\n";
            continue;
                }
                if (a > b)
                    swap(a, b);
                auto it1 = s.lower_bound(a);
                bool check1 = (*it1 >= a && *it1 <= b);
                bool check2 = false;
                auto it2 = s.lower_bound(b);
                if(it2!=s.end())check2 = true;
                if(*s.begin() <= a )check2 = true;
                if (check1 && check2 )
                    cout << "impossible\n";
                else
                {
                    cout << "possible\n";
                }
            }
        }

        return 0;

    
    
    
}