package backjoon;

// https://www.acmicpc.net/problem/2565

import java.io.BufferedReader;

import java.io.IOException;

import java.io.InputStreamReader;

import java.util.Arrays;

import java.util.Comparator;

import java.util.StringTokenizer;

public class _2565 {

public static void main(String[] args) throws IOException {

BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

int N = Integer.parseInt(br.readLine());

int[][] firstWire = new int[N][2];

int[] dp = new int[N];

StringTokenizer st;

for(int i = 0; i < firstWire.length; i++) {

st = new StringTokenizer(br.readLine()," ");

firstWire[i][0] = Integer.parseInt(st.nextToken());

firstWire[i][1] = Integer.parseInt(st.nextToken());

}

// 왼쪽 전봇대를 기준으로 2차원 배열 정렬

Arrays.sort(firstWire, new Comparator <int[]>() {

@Override

public int compare(int[] o1, int[] o2) {

return o1[0] - o2[0];

}

});

for(int i=0; i<dp.length; i++){

dp[i] = 1;

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

if(firstWire[i][1] > firstWire[j][1]){

dp[i] = Math.max(dp[i], dp[j]+1);

}

}

}

int max = 0;

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

max = Math.max(max, dp[i]);

}

// 전체 전선 개수 - 최대 설치가능 개수 = 최소 철거가능 개수

System.out.println(N-max);

}

}