怎么解啊

#include<iostream>
#include<cstdio>
#include<cstdlib>
#include<algorithm>
#include<cstring>
using namespace std;
int sum=0,mark[1001],word[1001],m,n,scaling=0,dic[101];//用dic[0]来存dic[m] 
int main()
{
    scanf("%d%d",&m,&n);
    for(int i=1;i<=n;i++) scanf("%d",&word[i]);
    for(int i=1;i<=n;i++)
    {
        if(mark[word[i]]) {
//            printf("i:%d\n",i);
            continue;    
        }
        else {
            sum++;
            scaling=(scaling+1)%m;
            if(dic[scaling]) mark[dic[scaling]]=0;
            dic[scaling]=word[i];
            mark[word[i]]=1;
//            printf("word[i]:%d\n",word[i]); 
        }
    }
    cout<<sum;
    return 0;
}