#include <bits/stdc++.h>
#define int long long
#define lint long long
#define pii pair<int,int>
#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define REP(i,n) FOR(i,0,n)
#define ALL(c) (c).begin(),(c).end()
#define ZERO(a) memset(a,0,sizeof(a))
#define MINUS(a) memset(a,0xff,sizeof(a))
#define MINF(a) memset(a,0x3f,sizeof(a))
#define POW(n) (1LL<<(n))
#define IN(i,a,b) (a <= i && i <= b)
using namespace std;
template <typename T> inline bool CHMIN(T& a,T b) { if(a>b) { a=b; return 1; } return 0; }
template <typename T> inline bool CHMAX(T& a,T b) { if(a<b) { a=b; return 1; } return 0; }
template <typename T> inline void SORT(T& a) { sort(ALL(a)); }
template <typename T> inline void REV(T& a) { reverse(ALL(a)); }
template <typename T> inline void UNI(T& a) { sort(ALL(a)); a.erase(unique(ALL(a)),a.end()); }
template <typename T> inline T LB(vector<T>& v, T a) { return *lower_bound(ALL(v),a); }
template <typename T> inline int LBP(vector<T>& v, T a) { return lower_bound(ALL(v),a) - v.begin(); }
template <typename T> inline T UB(vector<T>& v, T a) { return *upper_bound(ALL(v),a); }
template <typename T> inline int UBP(vector<T>& v, T a) { return upper_bound(ALL(v),a) - v.begin(); }
template <typename T1, typename T2> ostream& operator<< (ostream& os, const pair<T1,T2>& p) { os << p.first << " " << p.second; return os; }
template <typename T1, typename T2> istream& operator>> (istream& is, pair<T1,T2>& p) { is >> p.first >> p.second; return is; }
template <typename T> ostream& operator<< (ostream& os, const vector<T>& v) { REP(i,v.size()) { if (i) os << " "; os << v[i]; } return os; }
template <typename T> istream& operator>> (istream& is, vector<T>& v) { for(T& in : v) is >> in; return is; }
template <typename T = int> vector<T> make_v(size_t a) { return vector<T>(a); }
template <typename T, typename... Ts> auto make_v(size_t a, Ts... ts) { return vector<decltype(make_v<T>(ts...))>(a,make_v<T>(ts...)); }
template <typename T, typename V> typename enable_if<is_class<T>::value == 0>::type fill_v(T &t, const V &v) { t = v; }
template <typename T, typename V> typename enable_if<is_class<T>::value != 0>::type fill_v(T &t, const V &v) { for(auto &e : t) fill_v(e,v); }
const lint MOD = 1000000007;
const lint INF = 0x3f3f3f3f3f3f3f3f;
const double EPS = 1e-10;

int n, m;
int a[100010];
vector<int> v[100010];
int cnt[100010];

void _main() {
    cin >> n >> m;
    REP(i, n) {
        cin >> a[i];
        if (i) {
            v[a[i]].push_back(a[i - 1]);
            if (a[i - 1] < a[i]) {
                cnt[a[i - 1] + 1]++;
                cnt[a[i]]--;
            } else if (a[i - 1] > a[i]) {
                cnt[1]++;
                cnt[m + 1]--;
                cnt[a[i]]--;
                cnt[a[i - 1] + 1]++;
            }
        }
    }
    for (int i = 1; i < m; i++) {
        cnt[i + 1] += cnt[i];
    }
    int sum = 0;
    REP(i, n - 1) {
        sum += min((a[i + 1] + m - a[i]) % m, 1 + (a[i + 1] + m - 1) % m);
    }
    int ans = sum;
    FOR(i, 2, m + 1) {
        int newSum = sum;
        for (int j = 0; j < v[i - 1].size(); j++) {
            newSum += ((i - 1) + m - v[i - 1][j]) % m - 1;
        }
        newSum -= cnt[i - 1];
        CHMIN(ans, newSum);
        sum = newSum;
    }
    cout << ans << endl;
}

signed main(signed argc, char **argv) {
    if (argc > 1) {
        freopen("input.txt", "r", stdin);
        freopen("output.txt", "w", stdout);
    }
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    cout << fixed << setprecision(10);
    _main();
    return 0;
}

Measured memory_bytes: 6528