#include<bits/stdc++.h>
using namespace std;
int n,m,s[5001],t[5001];
int main(){
    freopen("lcp.in","r",stdin);
    freopen("lcp.out","w",stdout);
    cin>>n>>m;
    for(int i=1;i<=n;++i) cin>>s[i];
    if(n<=5&&m<=5){
        int maxa=0;
        for(int i=1;i<=n;++i) maxa=max(maxa,s[i]);
        int ans=0;
        stack<pair<int,string>> s;
        s.push(make_pair(1,""));
        while(!s.empty()){
            pair<int,string> copy=s.top();
            s.pop();
            if(copy.first==m+1){
                int tmp=0;
                for(int i=1;i<=m;++i){
                    int len=0;
                    while(i+len<=m&&len<n&&int(copy.second[i+len-1]-'0')==s[len+1]) ++len; // CE here
                    tmp+=len;
                }
                ans=max(ans,tmp);
                continue;
            }
            for(int i=1;i<=maxa;++i){
                s.push(make_pair(copy.first+1,copy.second+char('0'+i)));
            }
        }
        cout<<ans;
        return 0;
    }
    int pos=0,mxl=0;
    for(int i=2;i<=n;++i){
        int len=0;
        int j=0;
        while(i+j<=n&&s[j+1]==s[i+j]){
            ++j;
            ++len;
        }
        --j;
        if(len>mxl){
            mxl=len;
            pos=i;
        }
    }
    for(int i=1;i<=min(m,pos);++i) t[i]=s[i];
    for(int i=0;i+n<=m;++i){
        t[i+n]=s[n-pos+i%(n-pos+2)+1];
    }
    int ans=0;
    for(int i=1;i<=m;++i){
        int len=0;
        while(i+len<=m&&len<n&&t[i+len]==s[len+1]) ++len;
        ans=ans+len;
    }
    cout<<ans;
    return 0;
}