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

#define rep(i, a, b) for(int i = a; i < (b); ++i)

int main() {
    cin.tie(0)->sync_with_stdio(0);

    int n; cin >> n;
    vector<array<int, 2>> v(n);
    rep(i,0,n) {
        int r, g; cin >> r >> g;
        v[i] = {r, r + g};
    }

    int i = 1;
    while (true) {
        bool ok = true;
        for (auto && [r, p] : v) {
            if (i % p < r) {
                ok = false;
                break;
            }
        }
        if (ok) {
            cout << i << "\n";
            return 0;
        }
        ++i;
    }
}