#include using namespace std; using ll = long long; #define rep(i, s, n) for (int i = (s); i < (int)(n); i++) #define rep2(i, n, s) for (int i = (n - 1); i >= (s); i--) #define all(a) (a).begin(),(a).end() #define all_c(a, b) (a).begin(), (a).end(), back_inserter((b)) vector dy = {-1, 0, 1, 0, -1, -1, 1, 1}; vector dx = {0, 1, 0, -1, -1, 1, 1, -1}; const ll INF = numeric_limits::max(); const ll MOD = 1'000'000'007; ll unused = INF % MOD; ll gcd(ll A, ll B) { if (B == 0) return A; return gcd(B, A % B); } ll lcm(ll A, ll B) { ll g = gcd(A, B); return A / g * B; } // 二分検索の雛型 bool binary_search(int N, int A[], int K) { int left = 0, right = N - 1; while (left <= right) { int mid = (left + right) / 2; if (A[mid] == K) return true; if (A[mid] < K) left = mid + 1; else right = mid - 1; } return false; } /* lower_bound -> if (A[mid] < K) upper_bound -> if (A[mid] <= K) */ int binary_search2(int N, ll A[], ll K) { int left = 0, right = N; while (left < right) { int mid = (left + right) / 2; if (A[mid] < K) left = mid + 1; else right = mid; } return right; } /* メモ帳 ・小数点以下表示 / cout << fixed << setprecision(12) << ・ルートの計算 / sqrt(A) ・順列全列挙 do { } while (next_permutation(V.begin() V.end())); ・bit検索 for (int i = 0; i < (1 << N); i++) { rep(j, 0, N) { int wari = (1 << j); if ((i / wari) % 2 == 1) { } } } */ int N, Q, L[100009], R[100009], O[100009], ans = 0; int main() { cin >> N >> Q; rep(i, 0, Q) cin >> L[i] >> R[i]; rep(i, 1, N + 1) O[i] = 0; rep(i, 0, Q) { rep(j, L[i], R[i] + 1) { if (O[j]) { ans--; O[j] = 0; } else { ans++; O[j] = 1; } } cout << ans << endl; } }