#include <bits/stdc++.h>

using namespace std;

#define MAX 505
int col[MAX], val[MAX], change[MAX];

bool check(int i, int j)
{
    if(col[i] == col[j]) return val[i]>val[j];
    return change[col[i]] > change[col[j]];
}

int main()
{
    int c, n;
    scanf("%d %d", &c, &n);
    for(int i=0; i<c*n; i++){
        scanf("%d %d", &col[i], &val[i]);
    }
    vector<int> order, stop;
    for(int i=1; i<=c; i++) order.push_back(i);
    stop = order;
    int maxs = 0;
    while(1){
        for(int i=0; i<order.size(); i++){
            change[order[i]] = i+1;
        }
        int dp[n*c];
        for(int i=0; i<n*c; i++) dp[i] = 1;
        for(int i=1; i<n*c; i++){
            for(int j=0; j<i; j++){
                if(check(i, j)) dp[i] = max(dp[i], 1+dp[j]);
            }
            maxs = max(maxs, dp[i]);
        }
        next_permutation(order.begin(), order.end());
        if(order == stop) break;
    }
    cout << n*c-maxs;
}