cf 879A

#include <bits\stdc++.h>

using namespace std;

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

    int s[n], d[n];
    for(i = 0; i < n; i++) cin >> s[i] >> d[i];
    for(i = 1; i < n; i++)
    {
        while(s[i-1] >= s[i]) s[i] += d[i];
    }
    //for(i = 0; i < n; i++) cout << s[i] << endl;
    cout << s[n-1] << endl;
}