n=int(input())
list1=[]
list2=[]
flag=1
min,max=map(int,input().split())
for i in range(n-1):
x,y=map(int,input().split())
if(x<=min and y>=max):
min=x
max=y
flag=i+2
elif(x<min):
min=x
flag=-1
elif(y>max):
max=y
flag=-1
print(flag)#include<bits/stdc++.h>
using namespace std;
#define int long long
int32_t main()
{
int n;
cin>>n;
vector <pair <int,int> > v(n);
int mx=INT_MIN;
int mn=INT_MAX;
for(int i=0;i<n;i++)
{
cin>>v[i].first>>v[i].second;
mn=min(v[i].first,mn);
mx=max(v[i].second,mx);
}
int m=0;
for(int i=0;i<n;i++)
{
if(v[i].first==mn&&v[i].second==mx) {
cout<<i+1<<endl;
m++;
break;
}
}
if(m==0) cout<<"-1"<<endl;
}337B - Routine Problem | 1392D - Omkar and Bed Wars |
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1555B - Two Tables | 1686A - Everything Everywhere All But One |
1469B - Red and Blue | 1257B - Magic Stick |
18C - Stripe | 1203B - Equal Rectangles |
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1506C - Double-ended Strings | 340A - The Wall |
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1527A - And Then There Were K | 1618E - Singers' Tour |
1560B - Who's Opposite | 182B - Vasya's Calendar |