#include<cstdio>
using namespace std;
int M,N;
int queue[10000],head=0,tail=0;
bool book[1000+1]={};
int ans=0;
int main(){
    scanf("%d%d",&M,&N);
    for(int i=1;i<=N;i++){
        int word;
        scanf("%d",&word);
        if(tail-head==M)book[queue[head++]]=false;
        if(!book[word])ans++;
        book[word]=true;
        queue[tail++]=word;
    }
    printf("%d",ans);
    return 0;
}