// solution for https://www.hackerrank.com/challenges/even-tree

gistfile1.txt

// solution for https://www.hackerrank.com/challenges/even-tree
#include <iostream>
#include <fstream>
#include <map>
#include <deque>
#include <vector>
 
#include <cstring>
#include <algorithm>
 
using namespace std;
#define coutfpre(n,f) (setiosflags(ios::fixed)<<setprecision(n)<<f)
#define zero(n) memset(n,0,sizeof(n))
#define m1set(n) memset(n,-1,sizeof(n))
#define min(m,n) ((m<n)?m:n)
#define max(m,n) ((m>n)?m:n)
 
 
//#define FILE_TEST
 
int countAllChildren(vector <int> *v , int *childrens , int offset)
{
int totalSize = 0;
if(v[offset].size() == 0)
childrens[offset] = 1;
else if(0 == childrens[offset])
{
for(int i = 0; i < v[offset].size() ; i++)
{
totalSize += countAllChildren(v,childrens,v[offset][i]);
}
}
childrens[offset] = totalSize + 1;
return childrens[offset];
}
 
bool solve(istream &in,ostream &out)
{
int N,M;
int returnValue = 0;
in >> N >> M;
int childrens[N];
zero(childrens);
vector <int> childrenVector[N];
 
for(int i = 0; i < M ; i++)
{
int edge1,edge2;
in >> edge1 >> edge2;
edge1 --;
edge2 --;
childrenVector[edge2].push_back(edge1);
}
 
countAllChildren(childrenVector,childrens,0);
for(int i = 1; i < N; i++)
{
if((childrens[i])%2 == 0)
{
returnValue++;
}
}
 
out<<returnValue<<endl;
return true;
}
 
 
 
int main()
{
bool bSolved;
#ifdef FILE_TEST
ifstream in("in.txt");
ofstream out("out.txt");
if(!in)
{
cout<<"file in error\n";
return 0;
}
if(!out)
{
cout<<"file out error\n";
in.close();
return 0;
}
bSolved = solve(in,out);
in.close();
out.close();
#else
bSolved = solve(cin,cout);
#endif
 
#ifdef FILE_TEST
if(!bSolved)
cout << "not solved\n" <<endl;
else
cout << "solved\n" <<endl;
getchar();
#endif
 
return bSolved;
}