#include<cstdio>
#include<algorithm>
using namespace std;

int main() {
    int n; scanf("%d", &n);
	int p = 0, maxk = 0;
	for(int i = 0; i < n; i++) {
		int k, a; scanf("%d %d", &k, &a);
		maxk = max(k, maxk);
		int m = 0, s = 1;
		while(s < a) {
			s *= 4;
			m++;
		}
		p = max(p, k+m);
	}
	if(p == maxk) {
		p++;
	}
	printf("%d\n", p);
}