#include <iostream>
#include <deque>
#include <fstream>
#include <algorithm>
using namespace std;

int v[400005],Suma;
deque<int> dp;

int main()
{
    int n,x,p,maxim=0,start,dupa;
    ifstream f("buline.in");
    ofstream g("buline.out");
    f>>n;
    for(int i=1;i<=n;i++)
    {
        f>>x>>p;
        if(p==0)
        {
            v[i]=-x;
            v[n+i]=-x;
        }
        else
        {
            v[i]=x;
            v[n+i]=x;
        }
    }

    for(int i=1;i<=2*n;i++)
    {
        if(dp.size()==n)
        {
            Suma-=dp.front();
            dp.pop_front();
        }
        if(Suma+v[i]>v[i])
         {
            dp.push_back(v[i]);
            Suma+=v[i];
         }
         else
         {
            Suma=v[i];
            while(dp.size())
                dp.pop_front();
            dp.push_back(v[i]);
         }
        if(Suma>maxim)
        {
            maxim=Suma;
            dupa=dp.size();
            start=(i-dp.size())%n+1;
        }
    }
    g<<maxim;//<<" "<<start<<" "<<dupa;
    return 0;
}