#include<iostream>
#include<cstdio>
#include<algorithm>
#include<cstring>
using namespace std;
typedef long long ll;
int main(){
	freopen("goz.in","r",stdin);
	freopen("goz.out","w",stdout);
	const int INF=0x7fffffff;
	int N;
	scanf("%d",&N);
	int mindta=INF;
	ll ans=0;
	int a,b;
	bool flag=false;
	for(int i=1;i<=N;i++){
		scanf("%d%d",&a,&b);
		if(a>=b){
			flag=true;
			ans+=a;
		}
		else{
			ans+=b;
			mindta=min(mindta,b-a);
		}
	}
	if(!flag) ans-=mindta;
	cout<<ans<<endl;
	return 0;
}