呃呃呃，上一个貌似没有人看到？（
#include<bits/stdc++.h>
using namespace std;
int n;
const int maxn = 2e5 + 10;
struct node
{
int x,y;
bool operator <(const node & b)const
{
if(x == b.x)
{
return y < b.y;
}
return x < b.x;
}
}a[maxn],stk[maxn];
int top;
int serch(node x)
{
int l = 1,r = top,ans = 0;
while(l <= r)
{
int mid = l + r >> 1;
if(stk[mid] < x)
{
r = mid - 1;
ans = mid;
}
else
{
l = mid + 1;
}
}
return ans;
}
int solve(int l,int r)
{
if(l >= r)return 0;
int mid = l + r >> 1;
int ans = solve(l,mid) + solve(mid + 1,r);
for(int i = mid + 1;i <= r;i++)
{
while(stk[top].x <= a[i].x && top > 0)
{
top--;
}
stk[++top] = a[i];
}
for(int i = l;i <= mid;i++)
{
ans += serch(a[i]);
}
return ans;
}
int main()
{
cin >> n;
for(int i = 1;i <= n;i++)
{
cin >> a[i].x >> a[i].y;
}
sort(a + 1,a + n + 1);
cout << solve(1,n);
return 0;
}