#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define pii pair<int, int>
#define ull unsigned ll
#define f first
#define s second
#define FOR(i,a,b) for (int i=(a); i<(b); ++i)
#define REP(i,n) FOR(i,0,n)
#define RREP(i,n) for (int i=(n-1); i>=0; --i)
#define REP1(i,n) FOR(i,1,n+1)
#define ALL(x) x.begin(),x.end()
#define SZ(x) (int)x.size()
#define SQ(x) (x)*(x)
#define MN(a,b) a = min(a,(__typeof__(a))(b))
#define MX(a,b) a = max(a,(__typeof__(a))(b))
#define pb push_back
#define SORT_UNIQUE(c) (sort(c.begin(),c.end()), c.resize(distance(c.begin(),unique(c.begin(),c.end()))))
#ifdef BALBIT
#define IOS()
#define bug(...) fprintf(stderr,"#%d (%s) = ",__LINE__,#__VA_ARGS__),_do(__VA_ARGS__);
template<typename T> void _do(T &&x){cerr<<x<<endl;}
template<typename T, typename ...S> void _do(T &&x, S &&...y){cerr<<x<<", ";_do(y...);}
#else
#define IOS() ios_base::sync_with_stdio(0);cin.tie(0);
#define endl '\n'
#define bug(...)
#endif
const int iinf = 1<<29;
const ll inf = 1ll<<60;
const ll mod = 1e9+7;
void GG(){cout<<"-1\n"; exit(0);}
ll mpow(ll a, ll n, ll mo = mod){ // a^n % mod
ll re=1;
while (n>0){
if (n&1) re = re*a %mo;
a = a*a %mo;
n>>=1;
}
return re;
}
ll inv (ll b){
return b==1?1:(mod-mod/b) * inv(mod%b) % mod;
}
const int maxn = 1e5+5;
int nof[maxn][10]; // Number of this color, 0-based
int a[maxn];
int dp[maxn];
signed main(){
IOS();
int n, m; cin>>n>>m;
REP(i,n){
cin>>a[i]; -- a[i];
}
REP(M,m){
int re = iinf;
REP(M2,m){
dp[0]=0;
REP1(i,n){
dp[i] = iinf;
if (i == 1 || i == n) {
MN(dp[i], dp[i-1] + (a[i-1]!=M && a[i-1]!=M2));
}
if (i > 1){
MN(dp[i], dp[i-2] + min((a[i-1]!=M)+(a[i-2]!=M),(a[i-1]!=M2)+(a[i-2]!=M2)));
}
}
MN(re, dp[n]);
}
cout<<re<<endl;
}
// Check your array bounds!
// Think about corner cases (smallest or biggest?)
}
