#include <bits/stdc++.h>
using namespace std;
bool able[100004] = {1};
int main()
{
int num,q;
cin>>num>>q;
int ans=0;
for(int i=0;i<q;i++)
{
int l,r;
cin>>l>>r;
if(able[r] == false) ans++;
able[l] = true;
}
cout<<ans;
}
#include <bits/stdc++.h>
using namespace std;
bool able[100004] = {1};
int main()
{
int num,q;
cin>>num>>q;
int ans=0;
for(int i=0;i<q;i++)
{
int l,r;
cin>>l>>r;
if(able[r] == false) ans++;
able[l] = true;
}
cout<<ans;
}