5 ЛКШ

//  #define pragma

#ifdef pragma
#pragma GCC optimize("Ofast,no-stack-protector,unroll-loops")
// #pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
#endif // pragma

#include<bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>

#define ll long long
#define all(x) begin(x), end(x)
#define pb push_back
#define x first
#define y second
#define int long long
#define zero(two) memset(two, 0, sizeof(two))

using namespace std;
using namespace __gnu_pbds;


typedef vector<int> vi;
typedef vector<bool> vb;
typedef pair<int, int> pii;
typedef long double ld;
typedef vector<vi> matrix;
template<typename T>
using kawaii_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;

const ld PI = atan2(0, -1);

void seriy() {
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
//    cout << fixed << setprecision(10);
    #if 0
        freopen("input", "r", stdin);
        freopen("output", "w", stdout);
    #endif
}

const int MAXN = 2e5 + 10;
const int INF = 1e15 + 7;
const int MAXLOG = 31;
const int MOD = 998244353;
const int BASE = 47;

matrix g, gt;
vi tp;
vb used;
vi col(MAXN);
vi t(MAXN);

void dfs(int u) {
    used[u] = 1;
    for(auto v : g[u]) {
        if(!used[v]) {
            dfs(v);
        }
    }
    tp.pb(u);
}

void dfs2(int u, int cur) {
    t[cur]++;
    col[u] = cur;
    for(auto v : gt[u]) {
        if(!col[v]) {
            dfs2(v, cur);
        }
    }
}

signed main() {
    seriy();
    int n, m;
    cin >> n >> m;
    // assert(n != 2 && m != 2);
    g.resize(n);
    gt.resize(n);
    used.resize(n);
    vector<pii> edges;
    for(int i = 0; i < m; i++) {
        int u, v;
        cin >> u >> v;
        u--;
        v--;
        edges.pb({u, v});
        g[u].pb(v);
        gt[v].pb(u);
    }
    for(int i = 0; i < n; i++) {
        if(!used[i]) {
            dfs(i);
        }
    }

    reverse(all(tp));
    int cur = 1;
    for(int i = 0; i < n; i++) {
        if(!col[tp[i]]) {
            dfs2(tp[i], cur);
            cur++;
        }
    }
    int cnt = 0;
    map<pii, bool> mp;
    for(auto i : edges) {
        if(col[i.x] == col[i.y]) {
            cnt++;
            cnt -= mp[{i.x, i.y}];
            mp[{i.x, i.y}] = 1;
        }
    }
    int ans = 0;
    for(int i = 0; i < t.size(); i++) {
        ans += t[i] * (t[i] - 1);
    }

    cout << ans - cnt;
    return 0;
}