#include <stdio.h>
#include <vector>


using namespace std;
const int NMAX = 100005;

vector<int> matrice [NMAX];
bool viz[NMAX];
int n,m,ct;

void DFS(int a)
{
    int i;
    viz[a]=true;
    ct++;
    for(i=0;i< matrice[a].size();++i)
    {
        if(!viz[matrice[a][i]])
            DFS(matrice[a][i]);
    }
}

int main()
{
    int i,x,y;
    freopen("dfs.in","r",stdin);
    freopen("dfs.out","w",stdout);
    scanf("%d%d\n",&n, &m);
    int a = 0;
    for(i = 0;i < m; ++i)
    {
        scanf("%d%d\n",&x,&y);
        matrice[x].push_back(y);
    }
    DFS(1);
    printf("%d\n", ct);
    return 0;
}