#include <iostream>
#include <fstream>
#include <deque>
using namespace std;
ifstream in("buline.in");
ofstream out("buline.out");
const int maxn = 400005;
deque <int> dq;
int sp[maxn];
int v[maxn];
int main()
{
    int n;
    in >> n;
    for(int i = 1; i <= n; i++)
    {
        int aux;
        in >> v[i] >> aux;
        if(aux == 0)
            v[i] = -v[i];
        v[i + n] = v[i];
    }
    for(int i = 1; i <= n * 2; i++)
        sp[i] = sp[i - 1] + v[i];
    for(int i = 1; i < n; i++)
    {
        while(!dq.empty() && v[dq.back()] >= v[i])
            dq.pop_back();
        dq.push_back(i);
    }
    int mx = 0;
    for(int i = n; i <= n * 2; i++)
    {
        while(!dq.empty() && v[dq.back()] >= v[i])
            dq.pop_back();
        dq.push_back(i);
        if(dq.front() <= i - n)
            dq.pop_front();
        mx = max(mx, v[i] - v[dq.front()]);
    }
    out << mx;
    return 0;
}