202012-2

//注意不能使用两重循环
#include <bits/stdc++.h>
using namespace std;
const int maxn=2e5+5;
struct node{
    int x,y;
}s[maxn];
struct node1{
    int x,y,a,b,sum;
}s1[maxn];
int cmp(node n1,node n2){
    return n1.x<n2.x; 
}
int cmp1(node1 t1,node1 t2){//根据rule1,rule2定义好规则 
    if(t1.sum==t2.sum)
        return t1.x<t2.x;
    return t1.sum<t2.sum;
}
int main(){
    int n;
    scanf("%d",&n);
    for(int i=1;i<=n;++i){
        scanf("%d%d",&s[i].x,&s[i].y);
    }//将每对值存储 
    sort(s+1,s+1+n,cmp);//从小到大排好序 
    //
    int k=1;
    s1[k].x=s[1].x;
    if(s[1].y==1)
        s1[k].b++;
    else
        s1[k].a++;
    for(int i=2;i<=n;++i){
        if(s[i].x == s1[k].x)
        {//目的是使得s1成功去重 
            if(s[i].y==1)
                s1[k].b++;
            else
                s1[k].a++;
        }
        else{
            k++;
            s1[k].x=s[i].x;
            if(s[i].y==1)
                s1[k].b++;
            else
                s1[k].a++;
        } 
    }
     int a=0;
    int b=0;
    int sum=0;
    for(int i=1; i<=k; i++)
    {
        sum+=s1[i].a;
        s1[i].a=sum;
    }
    sum=0;
    for(int i=k; i>=1; i--)
    {
        sum+=s1[i].b;
        s1[i].b=sum;
    }//分别对两种情况（大于1,小于0）：正向，反向统计 --->同时利用已失效的空间a,b 
    s1[0].a=0;
    for(int i=1; i<=k; i++)
        s1[i].sum=s1[i-1].a+s1[i].b;//归总求和 
    sort(s1+1,s1+1+k,cmp1);//找到最大的那个 
    printf("%d\n",s1[k].x);
    return 0;
}