#include <bits/stdc++.h>
using namespace std;
int64_t exp(int64_t a, int64_t b) {
  if (b == 0) return 1;
  int64_t c = exp(a, b / 2);
  c = c * c;
  if (b % 2 == 1) c = c * a;
  return c;
}
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  int n;
  cin >> n;
  int64_t ans = 0;
  for (int i = 0; i < n; i++) {
    int64_t k, a;
    cin >> k >> a;
    if (a == 1) {
      ans = max(ans, k + 1);
      continue;
    }
    int64_t x = 0;
    for (int64_t b = 16; b >= 1; b /= 2) {
      while (exp(4, b + x) < a) x += b;
    }
    ans = max(ans, k + x + 1);
  }
  cout << ans;
}
