#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef vector<int> vi;
typedef vector<ll> vl;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;

typedef int _loop_int;
#define REP(i,n) for(_loop_int i=0;i<(_loop_int)(n);++i)
#define FOR(i,a,b) for(_loop_int i=(_loop_int)(a);i<(_loop_int)(b);++i)
#define FORR(i,a,b) for(_loop_int i=(_loop_int)(b)-1;i>=(_loop_int)(a);--i)

#define DEBUG(x) cout<<#x<<": "<<x<<endl
#define DEBUG_VEC(v) cout<<#v<<":";REP(i,v.size())cout<<" "<<v[i];cout<<endl
#define ALL(a) (a).begin(),(a).end()

#define CHMIN(a,b) a=min((a),(b))
#define CHMAX(a,b) a=max((a),(b))

// mod
const ll MOD = 1000000007ll;
#define FIX(a) ((a)%MOD+MOD)%MOD

// floating
typedef double Real;
const Real EPS = 1e-11;
#define EQ0(x) (abs(x)<EPS)
#define EQ(a,b) (abs(a-b)<EPS)
typedef complex<Real> P;

int main(){
  int n,q;
  scanf("%d%d",&n,&q);
  vector<int> dp(n,0);
  vector<int> pd(n,0);
  int cur = 0;
  dp[0] = 1;
  pd[1] = 1;
  while(q--){
    // REP(i,n)printf("%d ",dp[i]);putchar('\n');
    // REP(i,n)printf("%d ",pd[i]);putchar('\n');
    int a,b;
    scanf("%d%d",&a,&b);
    --a;--b;
    swap(dp[a],dp[b]);
    swap(pd[a],pd[b]);
    if(dp[a])cur=a;
    if(dp[b])cur=b;
    if(cur>0)pd[cur-1]|=1;
    if(cur<n-1)pd[cur+1]|=1;
  }
    // REP(i,n)printf("%d ",dp[i]);putchar('\n');
    // REP(i,n)printf("%d ",pd[i]);putchar('\n');
  int ans = 0;
  REP(i,n)ans += dp[i]|pd[i];
  printf("%d\n",ans);
  return 0;
}
