#include<stdio.h>
using namespace std;
struct house
{
    int position, alcohol;
};
house h[101000];
int n,i;

int calc(int a)
{
    long long result = 0;
    int i;
    int last_pos = h[0].position;
    for(i=0;i<n;i++)
    {
        if(result >= 0 && (result <= (h[i].position - last_pos)))
        {
            result = 0;
        }
        else
        {
            result -= (long long) (h[i].position - last_pos);
        }
        result += (long long) h[i].alcohol - a;
        last_pos = h[i].position;
    }
    return result >= 0;
}
int main()
{
    scanf("%d", &n);
    int r=0, l=0, t;
    for(i=0;i<n;i++)
    {
        scanf("%d%d", &h[i].position, &h[i].alcohol);
        if(r < h[i].alcohol)
        {
            r = h[i].alcohol;
        }
    }

    while(l < r)
    {
        t = l +(r - l + 1) / 2;
        if(calc(t))
        {
            l =t;
        }
        else
        {
            r = t-1;
        }
    }
    printf("%d\n", r);
    return 0;
}