#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  cin >> n;
  int result = 0;
  for (int i = 0; i < n; i++) {
    int k, a;
    cin >> k >> a;
    long x = k * a;
    int c = 0;
    if (a % 4 == 0) a--;
    while (a) {
      a /= 4;
      c++;
    }
    result = (((result) < (k + c)) ? (k + c) : (result));
  }
  cout << result;
}
