#include<iostream>
#include<cstdio>
using namespace std;

int judge[1000+5]={0};
int M[1000+5]={0};
int ans=0;
int n,m;

int main()
{
scanf("%d%d",&m,&n);
int temp;
for(int i=0;i<n;i++)
{
scanf("%d",&temp);
if(judge[temp]==0)
{
judge[temp]=1;
if(i>=m)
judge[M[i%m]]=0;
M[i%m]=temp;
ans++;
}
}

printf("%d",ans);

//while(1);
return 0;

}