func_code_string: #include <bits/stdc++.h>   using namespace std;   template <class T1>   void deb(T1 e) {     cout << e << endl;   }   template <class T1, class T2>   void deb(T1 e1, T2 e2) {     cout << e1 <<     << e2 << endl;   }   template <class T1, class T2, class T3>   void deb(T1 e1, T2 e2, T3 e3) {     cout << e1 <<     << e2 <<     << e3 << endl;   }   template <class T1, class T2, class T3, class T4>   void deb(T1 e1, T2 e2, T3 e3, T4 e4) {     cout << e1 <<     << e2 <<     << e3 <<     << e4 << endl;   }   template <class T1, class T2, class T3, class T4, class T5>   void deb(T1 e1, T2 e2, T3 e3, T4 e4, T5 e5) {     cout << e1 <<     << e2 <<     << e3 <<     << e4 <<     << e5 << endl;   }   template <class T1, class T2, class T3, class T4, class T5, class T6>   void deb(T1 e1, T2 e2, T3 e3, T4 e4, T5 e5, T6 e6) {     cout << e1 <<     << e2 <<     << e3 <<     << e4 <<     << e5 <<     << e6          << endl;   }   template <class T>   T Abs(T x) {     return x > 0 ? x : -x;   }   template <class T>   inline T sqr(T x) {     return x * x;   }   long long Pow(long long B, long long P) {     long long R = 1;     while (P > 0) {       if (P % 2 == 1) R = (R * B);       P /= 2;       B = (B * B);     }     return R;   }   long long BigMod(long long B, long long P, long long M) {     long long R = 1;     while (P > 0) {       if (P % 2 == 1) {         R = (R * B) % M;       }       P /= 2;       B = (B * B) % M;     }     return R;   }   long long n, m;   vector<pair<long long, long long> > v;   long long mod = 1000000007LL;   long long stree[4 * 200050];   map<long long, int> M;   set<long long> S;   void update(int node, int left, int right, int pos, long long val) {     if (pos < left || right < pos) return;     if (left == right) {       stree[node] = val;       return;     }     int mid = (left + right) / 2;     update(node * 2, left, mid, pos, val);     update(node * 2 + 1, mid + 1, right, pos, val);     stree[node] = stree[node * 2] % mod + stree[node * 2 + 1] % mod;     return;   }   long long query(int node, int left, int right, int srch_l, int srch_r) {     if (srch_l <= left && right <= srch_r) return stree[node];     if (right < srch_l || left > srch_r) return 0;     int mid = (left + right) / 2;     long long ret1 = query(node * 2, left, mid, srch_l, srch_r);     ret1 %= mod;     long long ret2 = query(node * 2 + 1, mid + 1, right, srch_l, srch_r);     ret2 %= mod;     long long ret = (ret1 + ret2) % mod;     return ret;   }   vector<int> adj[200050];   int main(void) {     long long a, b;     cin >> n >> m;     for (int i = 0; i < m; i++) {       cin >> a >> b, v.push_back(make_pair(a, b));       S.insert(a);       S.insert(b);     }     S.insert(0);     S.insert(n);     int track = 0;     for (__typeof((S).begin()) it = (S.begin()); it != (S).end(); ++it)       M[*it] = track++;     n = (int)M.size() - 1;     update(1, 0, n, 0, 1);     for (int i = 0; i < (int)v.size(); i++) {       long long right = v[i].second;       right = M[right];       adj[right].push_back(i);     }     for (int i = 1; i < (int)M.size(); i++) {       long long val = 0;       for (int j = 0; j < (int)adj[i].size(); j++) {         int indx = adj[i][j];         int left = v[indx].first;         int right = v[indx].second;         left = M[left];         right = M[right];         val += query(1, 0, n, left, right);         val %= mod;       }       update(1, 0, n, i, val);     }     deb(query(1, 0, n, n, n));     return 0;   }   