#include<iostream>
#include<cstdio>
#include<cstdlib>
#include<cmath>
using namespace std;
long long n,a,b,change=2000000;
long long ans=0;
bool useA=false;
int main()
{
	freopen("goz.in","r",stdin);
	freopen("goz.out","w",stdout);
	cin>>n;
	long long i;
	for(i=1;i<=n;i++)
	{
		cin>>a>>b;
		change=min(change,b-a);
		ans+=max(a,b);
		if(a>=b)useA=true;
	}
	if(useA)cout<<ans<<endl;
	else
	{
		ans-=change;
		cout<<ans;
	}
	return 0;
}