#include <bits/stdc++.h>
#define inf 1000000
using namespace std;

const int mx=405;
int C,N,ans,color[6];
bool used[6];

struct Pair {
    int val,c;
    bool operator > (Pair A) {
        if (c==A.c) return val>A.val;
        else return color[c]>color[A.c];
    }
};

Pair cards[mx],aux[mx];
int DP[mx];

int solve (int pos)
{
    if (pos==0) return 1;
    if (DP[pos]!=-1) return DP[pos];

    DP[pos]=1;
    for(int i=0; i<pos; i++){
        if(cards[pos] > cards[i]){
            DP[pos] = max(DP[pos], 1 + solve(i));
        }
    }
    return DP[pos];
}

void permutation (int pos)
{
    if (pos==C+1) {
        memset(DP,-1,sizeof(DP));
        for(int i=0; i<N; i++){
            ans = max(ans, solve(i));
        }
        return;
    }

    for (int i=1;i<=C;i++) if (!used[i]) {
        used[i]=true;
        color[pos]=i;
        permutation (pos+1);
        used[i]=false;
    }
}

int main ()
{
    //freopen("CARDS.IN","r",stdin);
   // freopen("CARDS.OUT","r",stdout);
    //freopen("in.txt", "r", stdin);
    int i,n;

    scanf ("%d %d",&C,&n);
    N=C*n;
    for (i=0;i<N;i++) scanf ("%d %d",&cards[i].c,&cards[i].val);
    color[5]=5;
    permutation(1);
    printf ("%d\n",N-ans);

    return 0;
}