#include <algorithm>
#include <climits>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <ctime>
#include <iostream>
#include <sstream>
#include <functional>
#include <map>
#include <set>
#include <unordered_map>
#include <unordered_set>
#include <bitset>
#include <string>
#include <cstring>
#include <vector>
#include <queue>
#include <stack>
#include <deque>
#include <list>
#include <numeric>
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
typedef pair<ll,ll> P;
typedef pair<P,ll> PPI;
typedef pair<ll,P> PIP;
typedef vector<ll> vl;
typedef vector<vl> vvl;
typedef vector<P> vp;
#define PQ(T) priority_queue<T,vector<T>,greater<T>>
#define PQ2(T) priority_queue<T>
const double PI = 3.14159265358979323846;
const double EPS = 1e-12;
const ll INF = 1LL<<29;
const ll mod = 1e9+7;
#define REP(i,a,b) for(ll (i)=a;(i)<(ll)(b);++(i))
#define rep(i,n) REP(i,0,n)
#define rep1(i,n) REP(i,1,n+1)
#define repd(i,n,d) for(ll (i)=0;(i)<(ll)(n);(i)+=(d))
#define all(v) (v).begin(), (v).end()
#define pb(x) push_back(x)
#define mp(x,y) make_pair((x),(y))
#define mset(m,v) memset((m),(v),sizeof(m))
#define chmin(x,y) ((x)=min((x),(y)))
#define chmax(x,y) ((x)=max((x),(y)))
#define fst first
#define snd second
#define UNIQUE(x) (x).erase(unique(all(x)),(x).end())
#define DEBUG(x) cerr<<"line ("<<__LINE__<<")  "<<#x<<": "<<x<<endl;
template<class T> ostream &operator<<(ostream &os, const vector<T> &v){int n=v.size();rep(i,n)os<<v[i]<<(i==n-1?"":" ");return os;}

int main(){
	ll n, q;
	cin>>n>>q;
	vector<int> v(n+2);
	v[1] = 2;
	v[2] = 1;
	rep(i, q){
		int a, b;
		cin>>a>>b;
		for(int j = -1; j <= 1; j++){
			v[a+j] |= v[a]>>1;
			v[b+j] |= v[b]>>1;
			v[a] |= v[a+j]>>1;
			v[b] |= v[b+j]>>1;
		}
		swap(v[a], v[b]);
		for(int j = -1; j <= 1; j++){
			v[a+j] |= v[a]>>1;
			v[b+j] |= v[b]>>1;
			v[a] |= v[a+j]>>1;
			v[b] |= v[b+j]>>1;
		}
	}
	int cnt = 0;
	rep(i, n) if(v[i+1]) cnt++;
	cout<<cnt<<endl;
	return 0;
}
