#include <bits/stdc++.h>
using namespace std;
using ll = long long;
const ll MOD = 1000000007;
const long long INF = 1LL << 60;
#define rep(i,n) for(int i = 0; i < n; i++)
#define all(x) (x).begin(),(x).end()

int main() {
    int n, q, ans = 0;
    cin >> n >> q;
    vector<int> a(n+1);
    rep(i,q){
        int l, r;
        cin >>  l >> r;
        a[l-1]++;
        a[r]++;
    }
    int b;
    for(int x : a){
        b += x;
        if(b%2==1) ans++;
    }
    cout << ans << endl;
}