#include<bits/stdc++.h>
using namespace std;
int m,n;
queue<string>q;
bool findd(string x){
	int d=q.size();
	for(int i=1;i<=d;i++){
		string a=q.front();
		q.pop();
		if(a==x)return 1;
		q.push(a);
	}
	return 0;
}
void hefa(){while(q.size()>m)q.pop();}
int main(){
	//freopen("translate.in","r",stdin);
	//freopen("translate.out","w",stdin);
	int ans=0;
	cin>>m>>n;
	for(int i=1;i<=n;i++){
		string p;
		cin>>p;
		if(!findd(p))q.push(p),ans++; 
		hefa();
	}
	cout<<ans;
}