#include<bits/stdc++.h>
using namespace std;
map<string,int> mp;
int main(){
	int n,v1;
	string st_in;
	cin>>n;
	for(int i=1;i<=n;i++){
		scanf("%d",&v1);
		if(v1!=4){
			cin>>st_in;
		}
		if(v1==1){
			cin>>v1;
			mp[st_in]=v1;
			cout<<"OK\n";
		}
		if(v1==2){
			if(mp[st_in]!=0){
				cout<<mp[st_in]<<'\n';
			}else{
				puts("Not found");
			}
		}
		if(v1==3){
			bool fl=0;
			for(auto it=mp.begin();it!=mp.end();it++){
				if(it->first==st_in){
					mp.erase(it);
					puts("Deleted successfully");
					fl=1;
					break;
				}
			}
			if(!fl){
				puts("Not found");
			}
		}
		if(v1==4){
			int ans=0;
			for(auto it=mp.begin();it!=mp.end();it++){
				if(it->second!=0){
					ans++;
				}
			}
			cout<<ans<<'\n';
		}
	}
	return 0;
}