#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
int t[2000005],a[2000005];
ll dp[2000005];
int st[2000005],top,btm;
void read(int &x){
	x=0;
	char ch=getchar();
	while(ch<'0' || ch>'9')ch=getchar();
	while(ch>='0' && ch<='9'){
		x=(x<<1)+(x<<3)+ch-'0';
		ch=getchar();
	}
}
int n;
ll f(int x){
	return dp[x]+a[x+1]+a[x+1];
}
int main(){
	read(n);
	for(int i=1;i<=n;i++){
		scanf("%d%d",&t[i],&a[i]);
		while(top>0 && a[st[top]]<=a[i])top--;
		st[++top]=i;
	}
	for(int i=1;i<=top;i++)a[i]=a[st[i]],t[i]=t[st[i]];
	n=top;
	btm=1,top=0;
	int pos=0;
	for(int i=1;i<=n;i++){
//		printf("%d %d\n",t[i],a[i]);
		while(top>=btm && f(st[top])>=f(i-1))top--;
		st[++top]=i-1;
		while(pos<i && dp[pos]<=t[i]){
			if(top>=btm && st[btm]==pos)btm++;
			pos++;
		}
		dp[i]=1LL*a[pos]*2+t[i];
		if(top>=btm)dp[i]=min(dp[i],f(st[btm]));
//		printf("%lld ",dp[i]);
	}
	printf("%lld",dp[n]);
	return 0;
}