#include<iostream>
#include<cstdio>
#include<string>
#include<cstring>
#include<map>
using namespace std;
map<string, int>e;
int main()
{
    int n;
    cin >> n;
    for (int i = 0; i < n; i++)
    {
        int a, b; string c;
        cin >> a;
        if (a != 4)cin >> c;
        if (a == 1)
        {
            cin >> b;
            e[c] = b;
            cout << "OK" << endl;
        }
        else if (a == 2)
        {
            if (!e.count(c))cout << "Not found" << endl;
            else cout << e[c] << endl;
        }

        else if (a == 3)
        {
        if(e.count(c)){ e.erase(c); cout << "Deleted successfully" << endl; }
            else cout << "Not found" << endl;
        }
        else cout << e.size()<<endl;
    }

}