#include<iostream>
#include<cstdio>
#include<cmath>
#include<cstring>
using namespace std;
int main(){
	freopen("waterj.in","r",stdin);
	freopen("waterj.out","w",stdout);
	int n,m,s=0,t=0,g=0;
	cin>>n>>m;//a tongxue b longto
	int a[10000],b[100];s=n;
	bool c[10000];
	memset(b,0,sizeof(b));
	memset(c,0,sizeof(c));
	for(int i=0;i<n;i++)
		cin>>a[i];
	while(g!=m){
		t++;
		//cout<<g<<"  "<<m<<endl;
		for(int i=0;i<m;i++)
			for(int j=0;j<n;j++)
			if(b[i]==0 && c[j]==0)
				{c[j]=1;b[i]=a[i];break;}
		for(int i=0;i<m;i++){
			//printf("%d ",b[i]);
			if(b[i]!=0)b[i]--;
		    else {g++;if(g==m)break;}
		}
	
	}
	t--;
	cout<<t;
	return 0;
}