#include <bits/stdc++.h>
using namespace std;
const double eps = 1e-9;
const double PI = acos(-1.0);
const long long int mod = 1e9 + 7;
const int MAXN = 1e6 + 5;
void cp() {
  int n;
  cin >> n;
  int mx = 0;
  for (int i = 0; i < n; i++) {
    int k;
    long long int a;
    cin >> k >> a;
    int p = k;
    long long int val = 1;
    while (val < a) val *= 4, p++;
    if (a == 1) p++;
    mx = max(mx, p);
  }
  cout << mx;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  ;
  int t;
  t = 1;
  while (t--) {
    cp();
  }
  return 0;
}
