#include<bits/stdc++.h>
using namespace std;
int n,g;
map<string,string> m;
int main(){
	cin>>n;
	for(int i=1;i<=n;i++){
		cin>>g;
		if(g==1){
			string a;
			cin>>a;
			int nn;
			cin>>nn;
			m[a]=nn;
			cout<<"OK"<<endl;
		}
		else if(g==2){
			string a;
			cin>>a;
			if(m.find(a)==m.end()){
				cout<<"Not found"<<endl;
			}
			else{
				cout<<m[a]<<endl;
			}
		}
		
		else if(g==3){
			string a;
			cin>>a;
			if(m.find(a)==m.end()){
				cout<<"Not found"<<endl;
			}
			else{
				m.erase(a);
				cout<<"Deleted successfully"<<endl;
			}
		}
		else{
			cout<<m.size()<<endl;
		}
	}
}

在下一位蒟蒻，在线求助，为什么第二种方法总是不输出成绩