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10775.cpp

#include <iostream>
#include <list>
#include <map>
#include <unordered_map>
#include <vector>
#include <stack>
#include <unordered_set>
#include <set>

using namespace std;
int g, p;
int n, res(0);
set<int> s;
int main() {
    scanf("%d%d",&g,&p);
    for(int i = 1; i <= p; i++) s.insert(i);
    while(p--) {
        scanf("%d",&n);
        auto it = s.upper_bound(n);
        if(it == s.begin()) break;

        s.erase(prev(it));
        res++;
    }
    cout<<res;
}