#include<bits/stdc++.h>
using namespace std;
int n,m,a[10005];
int main(){
	scanf("%d%d",&n,&m);
	for(int i = 0;i<n;i++)
		scanf("%d",&a[i]);
	int t = m+1,ans = 0;
	while(t<=n+m){
		for(int i = 0;i<m;i++){
			a[i]--;
			if(a[i] == 0)a[i] = a[t++];   
		}
		ans++;
	}
	printf("%d",ans);
    return 0;
}