#include <bits/stdc++.h>
#define rep(i, n) for (int i = 0; i < n; i++)
using namespace std;

typedef long long ll;

int N, M;
vector<vector<int>> edge(200001);
vector<int> f(200001, -1);

int solve(int x) {
    //cout << "solve(" << x << ")\n";
    if (f[x] != -1) return f[x];
    if (x == N) {
        f[x] = x;
        return x;
    }
    int ret = x;
    rep(i, edge[x].size()) {
        ret = max(ret, solve(edge[x][i]));
        //cout << ret << "!\n";
    }
    f[x] = ret;
    return ret;
}

int main() {
    int B, C;
    cin >> N >> M;
    rep(i, M) {
        cin >> B >> C;
        edge[B].push_back(C);
    }
    /*
    rep(i, N + 1) {
        cout << i << " " << edge[i].size() << "\n";
        rep(j, edge[i].size()) {
            cout << edge[i][j] << " ";
        }
        cout << "\n";
    }
    */
    ll ans = 0;
    rep(i, N) {
        ans += solve(i + 1);
        //cout << i + 1 << " " << solve(i + 1) << "\n";
    }
    cout << ans << "\n";
}