#include <bits/stdc++.h>
using namespace std;

#define rep(i,n) for(int i=0;i<n;++i)
#define rrep(i,n) for(int i=n-1;i>=0;i--)

int wa_greedy1(const int n, const vector<int> &A, const vector<int> &B) {
	int aa = 0, bb = 0;
	rep(i, n) {
		if (A[i] < B[i]) aa += A[i];
		else bb += B[i];
	}
	return max(aa, bb);
}

int main() {
	cin.tie(nullptr);
	ios::sync_with_stdio(false);

	int n;
	cin >> n;

	vector<int> A(n), B(n);
	rep(i, n) {
		cin >> A[i] >> B[i];
	}

	int ans = wa_greedy1(n, A, B);

	cout << ans << endl;

	return 0;
}