import java.util.Scanner;

// Create by Inho 2018. 3. 13. 오후 12:30:32

// 2565 전깃줄

public class Study_2565 {

public static void main(String[] args) {

Scanner scanner = new Scanner(System.in);

int TC = scanner.nextInt();

int[] lis = new int[501];

int[] arr = new int[501];

int a;

for(int i=0;i<TC;i++){

int index = scanner.nextInt();

arr[index]=scanner.nextInt();

}

int size=1;

lis[0] =-1;

lis[size] = arr[1];

for(int i=0;i<501;i++){

if(arr[i] != 0){

if(lis[size] >= arr[i]){

a=lowerbound(lis,0,size,arr[i]);

lis[a] = arr[i];

}

else

lis[++size] = arr[i];

}

}

System.out.println(TC-size);

}

public static int lowerbound(int[] arr, int start, int end,int target){

while(start < end){

int mid =(start+end)/2;

int midVal = arr[mid];

if(midVal < target){

start = mid+1;

}else{

end = mid;

}

} return start;

}

}