Solution

#include <iostream>
using namespace std;

int N, A[1000001]; 

static int find_smallest_01_gap(void)
{
    int smallest_gap = 2000000, current_start = -1;
    for (int i = 0; i <= 1000000; i++)
        if (A[i] != 0) {
            if (current_start != -1 && A[current_start] != A[i] && i - current_start < smallest_gap)
                smallest_gap = i - current_start;
            current_start = i;
        }
    return smallest_gap;
}

static int num_sick_clusters(void)
{
    int last_state = 0, answer = 0;
    for (int i = 0; i <= 1000000; i++)
        if (A[i] != 0) {
            if (A[i] != last_state && A[i] == 1) answer++;
            last_state = A[i];
        }
    return answer;
}

static int num_sick_gaps(int r)
{
    int answer = 0, current_start = 0;
    for (int i = 0; i <= 1000000; i++)
        if (A[i] != 0) {
            if (current_start != 0 && A[current_start] == 1 && A[i] == 1 && i - current_start >= r)
                answer++;
            current_start = i;
        }
    return answer;
}

int main()
{
    int x, s;
    cin >> N;
    for (int i = 0; i < N; i++) {
        cin >> x >> s;
        if (s == 1) { A[x] = 1; }
        if (s == 0) { A[x] = -1; }
    }
    int r = find_smallest_01_gap();
    cout << num_sick_clusters() + num_sick_gaps(r) << "\n";
    return 0;
}