#include <bits/stdc++.h>
#define clr(str , charr) memset(str,charr, sizeof(str))
using namespace  std;
using namespace std::chrono;

const int mod =  1e9 +5;

#define test int t; cin>>t; while(t--)
#define print( i , output ) cout << "Case #" << i << ": " << output ;

#define ll long long
#define pi 3.1415926


#define l length()
#define preci(x) cout << fixed<<setprecision(x)
#define infmax LONG_LONG_MAX
#define infmin LONG_LONG_MIN
#define bit __builtin_popcountll /*It returns the numbers of set bits in an integer 
(the number of ones in the binary representation of the integer).*/

#define all(v)			(v).begin(),(v).end()
#define sz(v)			(((int)((v).size())))
void fast(){
 ios_base::sync_with_stdio(0);cin.tie(0); cout.tie(0);
}

void solve ()
{
    int x, y ; ll sum1 =0 , sum2 =0;
    int n; cin>>n; 
    while(n--)
    {
        cin>>x>>y; 
        sum1+=x;
        sum2+=y; 
    }
    
    cout << max(sum2 , sum1) + abs(sum1 - sum2) ;
}

int main() 
{
  //fast();
  //test
  solve();
  //calctime();
}