#include <bits/stdc++.h>
#ifdef CKISEKI
#define safe cerr<<__PRETTY_FUNCTION__<<" line "<<__LINE__<<" safe\n"
#define debug(a...) debug_(#a, a)
#define orange(a...) orange(#a, a)
using std::cerr;
template <typename ...T>
void debug_(const char *s, T ...a) {
    cerr << "\e[1;32m(" << s << ") = (";
    int cnt = sizeof...(T);
    (..., (cerr << a << (--cnt ? ", " : ")\e[0m\n")));
}
template <typename I>
void orange_(const char *s, I L, I R) {
    cerr << "\e[1;32m[ " << s << " ] = [ ";
    for (int f = 0; L != R; ++L)
        cerr << (f++ ? ", " : "") << *L;
    cerr << " ]\e[0m\n";
}
#else
#define safe ((void)0)
#define debug(...) ((void)0)
#define orange(...) ((void)0)
#endif

#define all(v) begin(v),end(v)

using namespace std;

constexpr int maxc = 1'000'000 + 5;
constexpr int maxn = 500 + 5;

int a[maxn][maxn];

bool exi[maxc];
int x_min[maxc], x_max[maxc];
int y_min[maxc], y_max[maxc];

int cnt[maxc];
int cur[maxc];

int main() {
    cin.tie(nullptr) -> sync_with_stdio(false);
    int n, m; cin >> n >> m;
    for (int i = 0; i < n; ++i)
        for (int j = 0; j < m; ++j)
            cin >> a[i][j];

    for (int i = 0; i < maxc; ++i) {
        x_min[i] = n;
        y_min[i] = m;
    }

    for (int i = 0; i < n; ++i) {
        for (int j = 0; j < m; ++j) {
            const int c = a[i][j];
            x_min[c] = min(x_min[c], i);
            x_max[c] = max(x_max[c], i);
            y_min[c] = min(y_min[c], j);
            y_max[c] = max(y_max[c], j);
            exi[c] = true;
            cnt[c]++;
        }
    }
    
    int ans = 0;
    for (int c = 0; c < maxc; ++c) {
        if (not exi[c]) continue;
        ans -= 1;
        for (int i = x_min[c]; i <= x_max[c]; ++i) {
            for (int j = y_min[c]; j <= y_max[c]; ++j) {
                if (++cur[a[i][j]] == cnt[a[i][j]]) ans++;
            }
        }
        for (int i = x_min[c]; i <= x_max[c]; ++i) {
            for (int j = y_min[c]; j <= y_max[c]; ++j) {
                --cur[a[i][j]];
            }
        }
    }
    cout << ans << '\n';
    return 0;
}