func_code_string: #include <bits/stdc++.h>   using namespace std;   const int mod = 1e9 + 7;   inline int add(int x, int y) {     x += y;     if (x >= mod) x -= mod;     return x;   }   inline int sub(int x, int y) {     x -= y;     if (x < 0) x += mod;     return x;   }   inline int mul(int x, int y) { return (x * 1ll * y) % mod; }   inline int powr(int a, long long b) {     int x = 1 % mod;     while (b) {       if (b & 1) x = mul(x, a);       a = mul(a, a);       b >>= 1;     }     return x;   }   inline int inv(int a) { return powr(a, mod - 2); }   vector<pair<int, int> > A, B;   bool cmp(const pair<int, int>& x, const pair<int, int>& y) {     return x.first < y.first || (x.first == y.first && x.second > y.second);   }   void go(vector<pair<int, int> >& X) {     vector<pair<int, int> > ret;     sort(X.begin(), X.end(), cmp);     for (int i = 0; i < X.size(); i++) {       int l1 = X[i].first, r1 = X[i].second;       while (!ret.empty()) {         int l2 = ret.back().first, r2 = ret.back().second;         if (l1 >= l2 && r1 <= r2)           ret.pop_back();         else           break;       }       ret.push_back(X[i]);     }     X = ret;   }   const int inv2 = (mod + 1) >> 1;   const int MAXN = 200005;   int dp[2][2][MAXN];   int dp1[2][2][MAXN];   int dp2[2][2][MAXN];   void ADD(int& a, int b) {     a += b;     if (a >= mod) a -= mod;   }   vector<int> P[2];   int main() {     int k, n, m;     scanf( %d , &(k));     scanf( %d , &(n));     scanf( %d , &(m));     int mn = 2e9, mx = -1;     for (int i = 1; i <= n; i++) {       int a, b;       scanf( %d , &(a));       scanf( %d , &(b));       A.push_back({a, b});     }     for (int i = 1; i <= m; i++) {       int a, b;       scanf( %d , &(a));       scanf( %d , &(b));       B.push_back({a, b});     }     go(A);     go(B);     P[0] = P[1] = {-1};     for (auto it : A) P[0].push_back(it.second);     for (auto it : B) P[1].push_back(it.second);     reverse(A.begin(), A.end());     reverse(B.begin(), B.end());     dp[0][0][0] = dp1[0][0][0] = dp2[0][0][0] = 1;     int cnt[2] = {0, 0};     int f[2] = {powr(2, k), 0};     while (!A.empty() || !B.empty()) {       int L, R, type;       if (A.empty()) {         L = B.back().first;         R = B.back().second;         type = 1;         B.pop_back();       } else if (B.empty()) {         L = A.back().first;         R = A.back().second;         type = 0;         A.pop_back();       } else {         int l1 = A.back().first, r1 = A.back().second;         int l2 = B.back().first, r2 = B.back().second;         if (l1 < l2 || (l1 == l2 && r1 < r2)) {           L = l1;           R = r1;           type = 0;           A.pop_back();         } else {           L = l2;           R = r2;           type = 1;           B.pop_back();         }       }       cnt[type]++;       for (int prevparity = 0; prevparity < 2; prevparity++) {         int newparity = prevparity ^ 1;         int ind =             lower_bound(P[type].begin(), P[type].end(), L) - P[type].begin();         int ind2 = lower_bound(P[type ^ 1].begin(), P[type ^ 1].end(), L) -                    P[type ^ 1].begin();         ADD(dp[type][newparity][cnt[type]],             mul(powr(2, L - 1), add(dp2[type][prevparity][ind - 1],                                     dp2[type ^ 1][prevparity][ind2 - 1])));         ADD(dp[type][newparity][cnt[type]],             sub(dp1[type][prevparity][cnt[type] - 1],                 dp1[type][prevparity][ind - 1]));       }       for (int parity = 0; parity < 2; parity++) {         dp2[type][parity][cnt[type]] =             add(dp2[type][parity][cnt[type] - 1],                 mul(powr(inv2, R), dp[type][parity][cnt[type]]));         dp1[type][parity][cnt[type]] =             add(dp1[type][parity][cnt[type] - 1], dp[type][parity][cnt[type]]);         f[parity] =             add(f[parity], mul(dp[type][parity][cnt[type]], powr(2, k - R)));       }     }     printf( %d n , sub(f[0], f[1]));   }   