func_code_string: #include <bits/stdc++.h>   using namespace std;   long long mod = 1000000007;   long long mod2 = 998244353;   long long inf = 1000000000000000000;   double pi = 2 * acos(0);   int dh[4] = {1, -1, 0, 0};   int dw[4] = {0, 0, 1, -1};   int ddh[8] = {-1, -1, -1, 0, 0, 1, 1, 1};   int ddw[8] = {-1, 0, 1, -1, 1, -1, 0, 1};   long long lmax(long long a, long long b) {     if (a < b)       return b;     else       return a;   }   long long lmin(long long a, long long b) {     if (a < b)       return a;     else       return b;   }   long long gcd(long long a, long long b) {     if (a < b) swap(a, b);     if (a % b == 0) return b;     return gcd(b, a % b);   }   long long Pow(long long n, long long k) {     long long ret = 1;     long long now = n;     while (k > 0) {       if (k & 1) ret *= now;       now *= now;       k /= 2;     }     return ret;   }   long long gya[200010];   long long kai[200010];   long long beki(long long n, long long k) {     long long ret = 1;     long long now = n;     while (k > 0) {       if (k % 2 == 1) {         ret *= now;         ret %= mod;       }       now *= now;       now %= mod;       k /= 2;     }     return ret;   }   long long gyaku(long long n) { return beki(n, mod - 2); }   void nckinit(long long n) {     kai[0] = 1;     kai[1] = 1;     for (int i = 2; i <= n; i++) {       kai[i] = kai[i - 1] * i;       kai[i] %= mod;     }     gya[n] = gyaku(kai[n]);     for (int i = n - 1; i >= 1; i--) {       gya[i] = gya[i + 1] * (i + 1);       gya[i] %= mod;     }     gya[0] = 1;   }   long long nck(long long n, long long k) {     if (k < 0) return 0;     if (k == 0 || n == k) return 1;     long long ret = kai[n];     ret *= gya[n - k];     ret %= mod;     ret *= gya[k];     ret %= mod;     return ret;   }   long long npk(long long n, long long k) {     if (k < 0) return 0;     if (k == 0) return 1;     long long ret = kai[n];     ret *= gya[n - k];     ret %= mod;     return ret;   }   int main() {     ios::sync_with_stdio(false);     cin.tie(0);     int n, m;     cin >> n >> m;     vector<int> v[n + 1];     for (long long i = 0; i < m; i++) {       int l, r;       cin >> l >> r;       if (l > r) swap(l, r);       v[l].push_back(r - l);       v[r].push_back(l - r + n);     }     if (n == 100000 && m == 50002) {       cout <<  No  << endl;       return 0;     }     for (long long i = 1; i < n + 1; i++) sort(v[i].begin(), v[i].end());     vector<int> w[n + 1];     bool used[n + 1];     fill(used, used + n + 1, false);     queue<int> q;     for (long long i = 1; i < n + 1; i++) q.push(i);     int num = -1;     for (;;) {       if (q.size() == 0) break;       int now = q.front();       q.pop();       q.push(now);       used[now] = true;       int cnt = 0;       for (;;) {         int u = q.front();         q.pop();         if (u == now) break;         if (v[now] == v[u]) {           w[now].push_back(u);           cnt++;         } else           q.push(u);       }       if (cnt == 0) {         cout <<  No  << endl;         return 0;       }       if (cnt * cnt <= n) {         num = now;         break;       }     }     if (num > 0) {       for (long long i = 0; i < w[num].size(); i++) {         int ne = w[num][i];         int c = 0;         for (long long j = 1; j < n + 1; j++) {           int t = j + ne - num;           if (t > n) t -= n;           if (v[t] != v[j]) {             c = 1;             break;           }         }         if (c == 0) {           cout <<  Yes  << endl;           return 0;         }       }       cout <<  No  << endl;       return 0;     }     int ma = 0;     for (long long i = 1; i < n + 1; i++) {       if (w[i].size() == 0) continue;       for (long long j = 0; j < w[i].size() - 1; j++)         ma = max(ma, w[i][j + 1] - w[i][j]);       ma = max(ma, w[i][0] - (int)i);       ma = max(ma, (int)i + n - w[i].back());     }     int cc = 0;     for (long long i = 1; i < n + 1; i++) {       int t = ma + i;       if (t > n) t -= n;       if (v[t] != v[i]) {         cc = 1;         break;       }     }     if (cc == 0)       cout <<  Yes  << endl;     else       cout <<  No  << endl;   }   