“经典”问

随机情况下是期望是O(1)的

// Problem: “经典”问题
// Contest: NowCoder
// URL: https://ac.nowcoder.com/acm/contest/11201/B
// Memory Limit: 524288 MB
// Time Limit: 4000 ms
// 2022-06-17 19:10:21
// 
// Powered by CP Editor (https://cpeditor.org)

#include<bits/stdc++.h>
using namespace std;

#define rep(i,l,r) for(int i=(l);i<=(r);i++)
#define per(i,l,r) for(int i=(l);i>=(r);i--)
#define ll long long
#define mset(s,t) memset(s,t,sizeof(t))
#define mcpy(s,t) memcpy(s,t,sizeof(t))
#define fi first
#define se second
#define pb push_back
#define all(x) (x).begin(),(x).end()
#define SZ(x) ((int)(x).size())
#define mp make_pair

typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef vector<int> vi;   
typedef vector<ll> Vll;               
typedef vector<pair<int, int> > vpii;
typedef vector<pair<ll, ll> > vpll;                        

const ll mod = 1e9 + 7;
//const ll mod = 998244353;
const double pi  = acos(-1.0);
inline ll ksc(ll x,ll y,ll mod)
{
    ll ans = 0;
    while (y) {
        if (y & 1)
            ans = (ans + x) %mod;
        y >>= 1;
        x = (x + x) %mod;
    }
    return ans;
}
inline ll qmi (ll a, ll b) {
    ll ans = 1;
    while (b) {
        if (b & 1) ans = ans * a;
        a = a * a;
        b >>= 1;
    }
    return ans;
}
inline int read () {
    int x = 0, f = 0;
    char ch = getchar();
    while (!isdigit(ch)) f |= (ch=='-'),ch= getchar();
    while (isdigit(ch)) x = x * 10 + ch - '0', ch = getchar();
    return f?-x:x;
}
template<typename T> void print(T x) {
    if (x < 0) putchar('-'), x = -x;
    if (x >= 10) print(x/10);
    putchar(x % 10 + '0');
}
inline ll sub (ll a, ll b) {
    return ((a - b ) %mod + mod) %mod;
}
inline ll add (ll a, ll b) {
    return (a + b) %mod;
}
// inline ll inv (ll a) {
    // return qmi(a, mod - 2);
// }
int a[10000001],c[10000002][2],n,m;
unsigned int rd;
inline int rnd(int mod,int seed)
{
    rd^=(1<<13);
    rd^=(rd>>7);
    rd^=(rd<<20);
    rd^=(rd>>3);
    rd^=(rd<<10);
    rd^=(rd<<5);
    rd^=(1<<2);
    return rd%mod+seed;
}
// 生成序列 a
void make_sequence()
{
    for(int i=1;i<=n;i++)
    {
        a[i]=i-1;
    }
    for(int i=1;i<=n;i++)
    {
        swap(a[i],a[rnd(n,1)]);
    }
}
// 生成一个询问，表示查询区间 [l,r] 的 mex 
pair<int,int> make_query()
{
    int l=rnd(n,1);
    int r=rnd(n+1-l,l);
    return make_pair(l,r);
}
 
void solve() {
    cin >> n >> m;
    ll ans = 0;
    make_sequence();
    vector<int> p(n);
    for (int i = 0; i < n; i ++)
        p[a[i]] = i;
    for (int i = 1; i <= m ;i ++) {
        auto [l, r] = make_query();
        int x = 0;
        l --, r --;
        while(x < n && p[x] >= l && p[x] <= r)
            x ++;
        ans ^= x;
    }
    cout << ans << endl;
    
}
int main () {
    // ios::sync_with_stdio(0),cin.tie(0), cout.tie(0);
    int t;
    t =1;
    //cin >> t;
    while (t --) solve();
    return 0;
}