func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     int n;     cin >> n;     stack<pair<int, int> > S;     S.push(make_pair(0, -1));     vector<pair<int, int> > ans;     for (int i = 0; i <= n; i++) {       int a;       if (i < n)         cin >> a;       else         a = 0;       while (S.top().first > a) {         pair<int, int> last = S.top();         S.pop();         ans.push_back(make_pair(last.second, i - 1));         last.first--;         if (last.first > S.top().first) S.push(last);       }       if (S.top().first != a) S.push(make_pair(a, i));     }     cout << ans.size() << endl;     for (int i = 0; i < ans.size(); i++)       cout << ans[i].first + 1 <<     << ans[i].second + 1 << endl;   }   