#include<iostream>
using namespace std;
int main(){
	int w[11000],n,m,time,next;
	cin >>n;
	cin >>m;
	for(int i=1;i<=n;i++){
		cin >>w[i];		
	}
	next=m+1;
	while(next <= n+m){
		for(int i=1;i<=m;i++){
			w[i]--;
			if(w[i] == 0){
				w[i]=w[next];
				next++;
			}
		}
		time++;
	}
	cout <<time;
	return 0;
}