#include<iostream>
#include<cstdio>
#include<cstring>
#define REP(i,a,b) for(int i=a;i!=b+1;++i)
#define CLR(c,x) memset(c,x,szieof(c))
#define maxn 30000000+10
#define INF ~0U>>2
using namespace std;

typedef long long LL;

int n;
int _a,_b;
LL A[maxn],B[maxn],C[maxn];

void read(){
	scanf("%d",&n);
	REP(i,1,n){
		scanf("%d%d",&_a,&_b);
		A[i]=_a;B[i]=_b;
		C[i]=B[i]-A[i];
	}
}

void work(){
	bool is_all_B=1;
	LL cnt=0LL;
	REP(i,1,n){
		if(B[i]>A[i])cnt+=B[i];
		else{
			is_all_B=0;
			cnt+=A[i];
		}
	}
	if(is_all_B){
		LL t=INF;
		REP(i,1,n)if(C[i]<t)t=C[i];
		cnt-=t;
	}
	printf("%lld\n",cnt);
}

void setIO(string s){
	string in=s+".in",out=s+".out";
	freopen(in.c_str(),"r",stdin);
	freopen(out.c_str(),"w",stdout);
}

int main(){
	
	setIO("goz");
	
	read();
	work();
	return 0;
}