#include<iostream>
#include<cstdio>
#include<string> 
#include<cstring>
#include<map>
using namespace std;
const int N=100;
int main()
{
	int n,p;
	int score;
	string s1;
	s1.resize(N);
	map<string,int>m;
	scanf("%d",&n);
	for(int i=0;i<n;i++)
	{
		scanf("%d",&p);
		switch(p)
		{
			case 1://插入 
				scanf("%s%d",&s1[0],&score);
				m[s1]=score;
				printf("OK\n");
				break;
			case 2://查找 
				scanf("%s",&s1[0]);
				if(m.find(s1)!=m.end())
				{
					printf("%d\n",m[s1]);
				}
				else
				{
					printf("Not found\n");
				}
				break;
			case 3://删除 
				scanf("%s",&s1[0]);
				if(m.find(s1)!=m.end())
				{
					m.erase(s1);
					printf("Deleted successfully\n");
				}
				else
				{
					printf("Not found\n");
				}
				break;
			case 4://输出学生个数 
				printf("%d\n",m.size());
				break;
		}
	}
	return 0;
}