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

int main(){
	int n;
	cin >> n;
	int64_t a[n], b[n];
	for(int i = 0; i < n; i++) cin >> a[i] >> b[i];
	if(n == 1){
		cout << min(a[0], b[0]) << endl;
		return 0;
	}
	int64_t chi_a = 0, chi_b = 0;
	for(int i = 0; i < n; i++){
		int64_t next_a = chi_a + a[i], next_b = chi_b + b[i];
		if(abs(chi_a - next_b) < abs(next_a - chi_b)){
			chi_b = next_b;
		}else{
			chi_a = next_a;
		}
	}
	cout << abs(chi_a - chi_b) << endl;
}