TRAM195 C++

#include <bits/stdc++.h>
using namespace std;
int maxx,s,a[1000000],b[1000000],n;

void nhap()
{
    cin>>n;
    for (int i=1;i<=n;i++)
        cin>>a[i]>>b[i];    
}
int main()
{
    //freopen("tram195.inp","r",stdin);
    //freopen("tram195.out","w",stdout);
    nhap();
    for (int i=1;i<=n;i++)
    {
        s = s-a[i]+b[i];
        if (s>maxx) maxx = s;
    }
    cout<<maxx;
}