机器翻译

#include<iostream>
#include<cstdio>
#include<cstring>
using namespace std;
const int maxn=1007;
const int maxm=1e6+7;
int a[maxn],head,tail,q[maxm],ans;
bool inq[maxm];
int main(){
    int N,M;cin>>M>>N;
    for(int i=1;i<=N;i++){
        cin>>a[i];
    }
    for(int i=1;i<=N;i++){
        if(!inq[a[i]]){
            q[++tail]=a[i];
            inq[a[i]]=true;
            ans++;
        }
        if(tail-head>M){
            inq[q[head+1]]=false;
            head++; 
        }
    }
    cout<<ans<<endl;
    return 0;
}

一开始竟一直写的是tail-head>3真是面向样例编程啊