#pragma GCC optimize("Ofast")
#include <iostream>
#include <vector>
#include <algorithm>
#include <map>
#include <queue>
#include <cstdio>
#include <ctime>
#include <assert.h>
#include <chrono>
#include <random>
#include <numeric>
#include <set>
#include <deque>
#include <stack>
#include <sstream>
#include <utility>
#include <cstring>
#include <unordered_map>
#include <unordered_set>
#include <tuple>
#include <array>
#include <bitset>
using namespace std;
typedef long long int ll;
typedef unsigned long long ull;

mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
ll myRand(ll B) {
    return (ull)rng() % B;
}
inline double time() {
    return static_cast<double>(chrono::duration_cast<chrono::nanoseconds>(chrono::steady_clock::now().time_since_epoch()).count()) * 1e-9;
}

int main(){
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    int n,m; cin >> n >> m;
    bool f = (n%2 == 0 and m == 0);
    vector<pair<int,int>> v(m);
    for(int i=0;i<m;i++){
        cin >> v[i].first >> v[i].second;
    }
    if(m){
        vector<int> vv;
        for(auto p:v){
            vv.push_back(p.first);
            vv.push_back(p.second);
        }
        sort(vv.begin(), vv.end());
        vv.erase(unique(vv.begin(), vv.end()),vv.end());
        vv.push_back(vv[0]+n);
        for(int j=0;j+1<vv.size();j++){
            if(vv[j]%2 == vv[j+1]%2) f = true;
        }
    }
    cout << 4+(f?1:0) << endl;
}