#include <bits/stdc++.h>
 
using namespace std;
 
const int lim = 100001;
int N, M, i;
vector<int> adj[lim];
bool visited[lim];
int cc = 0;
 
void dfs(int s)
{
    if (visited[s]) return;
    visited[s] = true;
    cc++;
    for (auto u : adj[s])
        dfs(u);
}
 
int main()
{
    ifstream infile("dfs.in");
    ofstream outfile("dfs.out");
    infile >> N >> M;
    for (i = 0; i < M; i++)
    {
        int n, m;
        infile >> n >> m;
        adj[n].push_back(m);
    }
 
    dfs(1);
 
    outfile << cc << "\n";
 
    return 0;
}