#include <iostream>
#include <fstream>
#include <algorithm>
#include <vector>

using namespace std;

inline int min(int a, int b) {
    if (a < b)
        return a;
    return b;
}

inline int max(int a, int b) {
    if (a > b)
        return a;
    return b;
}

const int inf = 0x3f3f3f3f;

int main() {
    ifstream cin("joc.in");
    ofstream cout("joc.out");
    int N; cin >> N;
    vector<int> best(101, 0);

    for (int i = 0; i < N;   i) {
        int d, p; cin >> d >> p;
        vector<int> newbest(101, inf);
        for (int j = 1; j <= 100;   j) {
            int newpoints = min(100, j   d);
            if (newpoints > p)
                newbest[newpoints - p] = min(newbest[newpoints - p], best[j]);

            newbest[newpoints] = min(newbest[newpoints], best[j]   1);
        }
        swap(best, newbest);
    }

    cout << *min_element(best.begin()   1, best.end()) << "\n";
}