Binge watching

input/code.cpp: In function 'int main()':
input/code.cpp:14:12: warning: unused variable 'm' [-Wunused-variable]
   14 |     int n, m, k;
      |            ^
input/code.cpp:14:15: warning: unused variable 'k' [-Wunused-variable]
   14 |     int n, m, k;
      |               ^

#include <algorithm>
#include <iostream>
#include <vector>
using namespace std;

struct sort_pred {
    bool operator()(const std::pair<int, int> &left, const std::pair<int, int> &right) {
        return left.second < right.second;
    }
};

int main() {
    int n, m, k;
    cin >> n;

    vector<pair<int, int>> movies(n);
    vector<pair<int, int>> movie_lengths(n);

    for (int i = 0; i < n; ++i) {
        cin >> movies[i].first >> movies[i].second;
        movie_lengths[i].first = movies[i].second - movies[i].first;
        movie_lengths[i].second = i;
    }

    // sort(movies.begin(), movies.end());
    sort(movie_lengths.begin(), movie_lengths.end());

    sort(movies.begin(), movies.end(), sort_pred());

    //(for (int i = 0; i < n; ++i) cout << '('  << movies[i].first << ' ' << movies[i].second << ')' << endl;

    int nmovies = 1;

    int last_end = movies[0].second;

    for (int i = 0; i <= n; ++i) {
        int startc = movies[i].first, endc = movies[i].second;
        if (last_end <= startc) {
            ++nmovies;
            last_end = endc;
        }

    }

            std::cout << nmovies << endl;

}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: WRONG ANSWER

Test 8

Verdict: WRONG ANSWER

Test 9

Verdict: ACCEPTED