求助大佬

#include<cstdio>
#include<iostream>
#include<algorithm>
using namespace std;
int n,a[5005],b[5005],ans,dp[5005];
int main(){
	cin>>n;
	for(int i=1;i<=n;i++) cin>>a[i]>>b[i];
	for(int i=1;i<=n;i++)
	{
		dp[i]=1;
		for(int j=1;j<=i-1;j++)
		{
			if(a[i]<=a[j]&&b[i]<=b[j])
			dp[i]=max(dp[i],dp[j]+1);
		}
		ans=max(ans,dp[i]);
	}
	cout<<n-ans+1<<endl;;
	return 0;
}