Kampanja

#include <bits/stdc++.h>

using namespace std;

int main()
{
    int n, c;
    cin >> n >> c;

    vector<int> diff;
    for (int i = 0; i < c; ++i) {
        int p, r;
        cin >> p >> r;
        diff.push_back(p - r);
    }

    sort(diff.begin(), diff.end());

    int COUNT = 0;
    int i = 0;
    while (n-diff[i] > 0 && i < diff.size()) {
        n -= diff[i];
        i++;
        COUNT++;
    }

    cout << COUNT << endl;

    return 0;
}