#include <bits/stdc++.h>

using namespace std;

bool check(vector<vector<int>> &a, int k)
{
    int rich = k - 1;
    int poor = 0;
    int count = 0;
    for (int i = 0; i < a.size(); i++)
    {
        if (a[i][0] >= rich && a[i][1] >= poor)
        {
            rich--;
            poor++;
            count++;
        }
    }
    return count >= k;
}

int maximumQuestions(int N, vector<vector<int>> &A)
{

    int start = 1;
    int end = N;
    int ans = 0;
    while (start <= end)
    {
        int mid = start + (end - start) / 2;
        if (check(A, mid))
        {
            ans = mid;
            start = mid + 1;
        }
        else
        {
            end = mid - 1;
        }
    }

    return ans;
}

signed main()
{
    int N;
    cin >> N;

    vector<vector<int>> A(N, vector<int>(2));
    for (int i = 0; i < N; i++)
    {
        cin >> A[i][0] >> A[i][1];
    }

    cout << maximumQuestions(N, A) << endl;
}