#include <iostream>
#include <cstdio>
#include <map>
#include <string>
using namespace std;
int main()
{
int n;
map<string, int> system;//学籍管理系统的map
scanf("%d", &n);
for(int i = 1; i <= n; i++)
{
int zt;//状态
string name;
int score;
scanf("%d", &zt);
switch(zt)
{
case 1:
cin >> name >> score;
if(!system[name])
system[name] = score;
else
system[name] = score;
printf("OK\n");
break;
case 2:
cin >> name;
if(!system[name])
printf("Not Found\n");
else
printf("%d\n", system[name]);
break;
case 3:
cin >> name;
if(system[name])
{
system.erase(name);
printf("Deleted successfully\n");
}
else
printf("Not Found\n");
break;
case 4:
printf("%d\n", system.size());
break;
}
}
return 0;
}