// >>> TEMPLATES
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = long double;
using i32 = int32_t;
using i64 = int64_t;
using u32 = uint32_t;
using u64 = uint64_t;
#define int ll
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define rep1(i, n) for (int i = 1; i <= (int)(n); i++)
#define repR(i, n) for (int i = (int)(n)-1; i >= 0; i--)
#define rep1R(i, n) for (int i = (int)(n); i >= 1; i--)
#define loop(i, a, B) for (int i = a; i B; i++)
#define loopR(i, a, B) for (int i = a; i B; i--)
#define all(x) begin(x), end(x)
#define allR(x) rbegin(x), rend(x)
#define pb push_back
#define eb emplace_back
#define fst first
#define snd second
template <class Int> auto constexpr inf_ = numeric_limits<Int>::max()/2-1;
auto constexpr INF32 = inf_<int32_t>;
auto constexpr INF64 = inf_<int64_t>;
auto constexpr INF   = inf_<int>;
#ifdef LOCAL
#include "debug.hpp"
#define oj_local(x, y) (y)
#else
#define dump(...) (void)(0)
#define say(x) (void)(0)
#define debug if (0)
#define oj_local(x, y) (x)
#endif
template <class T, class Comp> struct pque : priority_queue<T, vector<T>, Comp> { vector<T> &data() { return this->c; } void clear() { this->c.clear(); } };
template <class T> using pque_max = pque<T, less<T>>;
template <class T> using pque_min = pque<T, greater<T>>;
template <class T, class = typename T::iterator, enable_if_t<!is_same<T, string>::value, int> = 0>
ostream& operator<<(ostream& os, T const& a) { bool f = true; for (auto const& x : a) os << (f ? "" : " ") << x, f = false; return os; }
template <class T, size_t N, enable_if_t<!is_same<T, char>::value, int> = 0>
ostream& operator<<(ostream& os, const T (&a)[N]) { bool f = true; for (auto const& x : a) os << (f ? "" : " ") << x, f = false; return os; }
template <class T, class = decltype(begin(declval<T&>())), class = typename enable_if<!is_same<T, string>::value>::type>
istream& operator>>(istream& is, T &a) { for (auto& x : a) is >> x; return is; }
template <class T, class S> ostream& operator<<(ostream& os, pair<T, S> const& p) { return os << p.first << " " << p.second; }
template <class T, class S> istream& operator>>(istream& is, pair<T, S>& p) { return is >> p.first >> p.second; }
struct IOSetup { IOSetup() { cin.tie(nullptr); ios::sync_with_stdio(false); cout << fixed << setprecision(15); } } iosetup;
template <class F> struct FixPoint : private F {
    constexpr FixPoint(F&& f) : F(forward<F>(f)) {}
    template <class... T> constexpr auto operator()(T&&... x) const { return F::operator()(*this, forward<T>(x)...); }
};
struct MakeFixPoint { template <class F> constexpr auto operator|(F&& f) const { return FixPoint<F>(forward<F>(f)); } };
#define MFP MakeFixPoint()|
#define def(name, ...) auto name = MFP [&](auto &&name, __VA_ARGS__)
template <class T, size_t d> struct vec_impl {
    using type = vector<typename vec_impl<T, d-1>::type>;
    template <class... U> static type make_v(size_t n, U&&... x) { return type(n, vec_impl<T, d-1>::make_v(forward<U>(x)...)); }
};
template <class T> struct vec_impl<T, 0> { using type = T; static type make_v(T const& x = {}) { return x; } };
template <class T, size_t d = 1> using vec = typename vec_impl<T, d>::type;
template <class T, size_t d = 1, class... Args> auto make_v(Args&&... args) { return vec_impl<T, d>::make_v(forward<Args>(args)...); }
template <class T> void quit(T const& x) { cout << x << endl; exit(0); }
template <class T, class U> constexpr bool chmin(T& x, U const& y) { if (x > (T)y) { x = (T)y; return true; } return false; }
template <class T, class U> constexpr bool chmax(T& x, U const& y) { if (x < (T)y) { x = (T)y; return true; } return false; }
template <class It> constexpr auto sumof(It b, It e) { return accumulate(b, e, typename iterator_traits<It>::value_type{}); }
template <class T> int sz(T const& x) { return x.size(); }
template <class C, class T> int lbd(C const& v, T const& x) { return lower_bound(begin(v), end(v), x)-begin(v); }
template <class C, class T> int ubd(C const& v, T const& x) { return upper_bound(begin(v), end(v), x)-begin(v); }
constexpr ll mod(ll x, ll m) { assert(m > 0); return (x %= m) < 0 ? x+m : x; }
constexpr ll div_floor(ll x, ll y) { assert(y != 0); return x/y - ((x^y) < 0 and x%y); }
constexpr ll div_ceil(ll x, ll y) { assert(y != 0); return x/y + ((x^y) > 0 and x%y); }
constexpr int dx[] = { 1, 0, -1, 0, 1, -1, -1, 1 };
constexpr int dy[] = { 0, 1, 0, -1, 1, 1, -1, -1 };
constexpr int popcnt(ll x) { return __builtin_popcountll(x); }
mt19937_64 seed_{random_device{}()};
template <class Int> Int rand(Int a, Int b) { return uniform_int_distribution<Int>(a, b)(seed_); }
i64 irand(i64 a, i64 b) { return rand<i64>(a, b); } // [a, b]
u64 urand(u64 a, u64 b) { return rand<u64>(a, b); } //
template <class It> void shuffle(It l, It r) { shuffle(l, r, seed_); }
template <class V> V &operator--(V &v) { for (auto &x : v) --x; return v; }
template <class V> V &operator++(V &v) { for (auto &x : v) ++x; return v; }
bool next_product(vector<int> &v, int m) {
    repR (i, v.size()) if (++v[i] < m) return true; else v[i] = 0;
    return false;
}
bool next_product(vector<int> &v, vector<int> const& s) {
    repR (i, v.size()) if (++v[i] < s[i]) return true; else v[i] = 0;
    return false;
}
template <class vec> int sort_unique(vec &v) {
    sort(begin(v), end(v));
    v.erase(unique(begin(v), end(v)), end(v));
    return v.size();
}
template <class It> auto prefix_sum(It l, It r) {
    vector<typename It::value_type> s = { 0 };
    while (l != r) s.emplace_back(s.back() + *l++);
    return s;
}
template <class It> auto suffix_sum(It l, It r) {
    vector<typename It::value_type> s = { 0 };
    while (l != r) s.emplace_back(*--r + s.back());
    reverse(s.begin(), s.end());
    return s;
}
template <class T> T pop(vector<T> &a) { auto x = a.back(); a.pop_back(); return x; }
template <class T, class V, class C> T pop(priority_queue<T, V, C> &a) { auto x = a.top(); a.pop(); return x; }
template <class T> T pop(queue<T> &a) { auto x = a.front(); a.pop(); return x; }
template <class T> T pop_front(deque<T> &a) { auto x = a.front(); a.pop_front(); return x; }
template <class T> T pop_back(deque<T> &a) { auto x = a.back(); a.pop_back(); return x; }
template <class T> T pop_front(set<T> &a) { auto x = *a.begin(); a.erase(a.begin()); return x; }
template <class T> T pop_back(set<T> &a) { auto it = prev(a.end()); auto x = *it; a.erase(it); return x; }
template <class T> T pop_front(multiset<T> &a) { auto it = a.begin(); auto x = *it; a.erase(it); return x; }
template <class T> T pop_back(multiset<T> &a) { auto it = prev(a.end()); auto x = *it; a.erase(it); return x; }
// <<<
// >>> hash value

struct Hash {
    using u64 = uint64_t;
    using i32 = int32_t;
    struct mint;
    Hash() {};
    Hash(mint val, i32 len) : val(val), len(len) {}
    // do not use for `const char*'
    template <class Str, class = typename Str::iterator>
    Hash(Str const& s) : val(0), len(0) {
        for (auto c : s) *this = *this + Hash(c);
    }
    template <class Int, enable_if_t<is_integral_v<Int>, int> = 0>
    Hash(Int x) : val(x ^ pow(1).x), len(1) {}
    Hash operator+(Hash const& r) const {
        return { val * pow(r.len) + r.val, len + r.len };
    }
    Hash operator-() const { return { - pow(-len) * val, -len }; }
    Hash operator-(Hash const& r) const { return *this + (-r); }
    bool operator==(Hash const& r) const { return val == r.val && len == r.len; }
    bool operator!=(Hash const& r) const { return !(*this == r); }
    bool operator<(Hash const& r) const {
        return val.x == r.val.x ? len < r.len : val.x < r.val.x;
    }

    static constexpr u64 mod = (1ull<<61) - 1;
    struct mint {
        u64 x;
        constexpr mint(u64 x = 0) : x(x) {
            x = (x & mod) + (x >> 61);
            x = (x < mod ? x : x-mod);
        }
        constexpr bool operator==(mint const& r) const { return x == r.x; }
        constexpr bool operator!=(mint const& r) const { return x != r.x; }
        constexpr mint operator+() const { return *this; }
        constexpr mint operator-() const { return mint()-*this; }
        constexpr mint& operator+=(mint const& r) { x += r.x; x = (x < mod ? x : x-mod); return *this; }
        constexpr mint& operator-=(mint const& r) { x += mod-r.x; x = (x < mod ? x : x-mod); return *this; }
        constexpr mint& operator*=(mint r) { x = mul(x, r.x); return *this; }
        constexpr mint operator+(mint r) const { return mint(*this) += r; }
        constexpr mint operator-(mint r) const { return mint(*this) -= r; }
        constexpr mint operator*(mint r) const { return mint(*this) *= r; }
#ifdef LOCAL
        string to_s(mint x) { return to_s(x.x); }
#endif
    };

    mint val = 0;
    i32 len = 0;

    static mint pow(int n) {
        static u64 B = 0, iB = 1;
        if (B == 0) {
            mt19937_64 mt(random_device{}());
            B = uniform_int_distribution<u64>(300, mod-300)(mt);
#ifdef LOCAL
            B = 10000;
#endif
            u64 k = mod - 2, p = B;
            for ( ; k; k >>= 1, p = mul(p, p)) if (k & 1) iB = mul(iB, p);
        }
        if (n >= 0) {
            static vector<u64> pow(1, 1);
            if (n >= (int)pow.size()) {
                int m = pow.size();
                pow.resize(n + 1);
                for (int i = m; i < n + 1; i++) pow[i] = mul(pow[i-1], B);
            }
            return pow[n];
        } else {
            static vector<u64> pow(1, 1);
            n = -n;
            if (n >= (int)pow.size()) {
                int m = pow.size();
                pow.resize(n + 1);
                for (int i = m; i < n + 1; i++) pow[i] = mul(pow[i-1], iB);
            }
            return pow[n];
        }
    }
    static constexpr u64 mul(u64 a, u64 b) {
        auto val = __uint128_t(a) * b;
        val = (val & mod) + (val >> 61);
        return val >= mod ? val - mod : val;
        // constexpr u64 mask30 = (1ull << 30) - 1;
        // constexpr u64 mask31 = (1ull << 31) - 1;
        // u64 au = a >> 31, ad = a & mask31;
        // u64 bu = b >> 31, bd = b & mask31;
        // u64 mid = ad * bu + au * bd, midu = mid >> 30, midd = mid & mask30;
        // u64 val = au * bu * 2 + midu + (midd << 31) + ad * bd;
        // val = (val & mod) + (val >> 61);
        // return val >= mod ? val - mod : val;
    }
#ifdef LOCAL
    friend string to_s(Hash const& hash) {
        return to_s(make_pair(hash.val.x, hash.len));
    }
#endif
};

// <<<

int32_t main() {
    int n, m; cin >> n >> m;
    set<Hash> st;
    rep (i, n) {
        string s; cin >> s;
        vector<Hash> sub(m+1);
        repR (j, m) sub[j] = Hash(s[j]) + sub[j+1];
        set<Hash> A;
        rep (j, m+1) {
            Hash L = sub[0]-sub[j];
            Hash R = sub[j]-sub[m];
            rep (c, 26) A.insert(L + Hash('a'+c) + R);
        }
        if (i == 0) st = A;
        else {
            set<Hash> B;
            set_intersection(all(st), all(A), inserter(B, B.end()));
            swap(st, B);
        }
    }

    cout << st.size() << '\n';
}