map写法太简单了

#include <bits/stdc++.h>
using namespace std;
int n;
map<string,int> M;
int main(){
	cin>>n;
	for(int i=1;i<=n;i++){
		int sys;
		cin>>sys;
		if(sys==1){
			string s;
			int score;
			cin>>s>>score;
			M[s]=score;
			cout<<"OK"<<endl;
		}
		if(sys==2){
			string s;
			cin>>s;
			if(M.count(s)){
				cout<<M[s]<<endl;
			}
			else{
				cout<<"Not found"<<endl;
			}
		}
		if(sys==3){
			string s;
			cin>>s;
			
			if(M.count(s)){
				M.erase(s);
				cout<<"Deleted successfully"<<endl;
			}
			else{
				cout<<"Not found"<<endl;
			}
		}
		if(sys==4){
			cout<<M.size()<<endl;
		}
	}
}