#include <iostream>
#include <vector>
#include <algorithm>

/*
OKTV 2022 II. forduló
*/

using namespace std;

int main()
{
    long n, k;
    cin >> n >> k;
    long hand[k];
    for(long i=0; i<k; i++){
        cin >> hand[i];
    }
    vector<long> played;
    played.push_back(hand[0]);
    for(long i=1; i<k; i++){
        if(hand[i] > played.back()){
            played.push_back(hand[i]);
        }
    }

    sort(hand,hand+k);

    long points = 0;

    long interval_max = 1;
    bool wasPointInInterval = false;
    for(long i=1; i<k; i++){
        if(hand[i] != played.at(interval_max)){
            if(!wasPointInInterval){
                points++;
                wasPointInInterval = true;
            }
        }
        else{
            interval_max++;
            wasPointInInterval = false;
        }
    }

    cout << points << endl;

    return 0;
}
/*
25 7
1 8 3 15 4 20 16


1 3 4 8 15 16 20
*/