#include<bits/stdc++.h>
using namespace std;
struct xian{
    priority_queue<int> q;
}a[7];
int n,p;
long long ans;
int main()
{
    freopen("gitara.in","r",stdin);
    freopen("gitara.out","w",stdout);
    scanf("%d%d",&n,&p);
    for(int i=1;i<=n;i++)
    {
        int x,y;
        scanf("%d%d",&x,&y);
        while(a[x].q.size()&&a[x].q.top()>y)
        {
            a[x].q.pop();
            ans++;
        }
        if(a[x].q.size()==0||a[x].q.top()!=y)
        {
            a[x].q.push(y);
            ans++;
        }
    }
    printf("%lld",ans);
    return 0;
}