#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
typedef long long int ll;
typedef long double ld;
#define FOR(i,l,r) for(ll i=l;i<r;i++)
#define REP(i,n) FOR(i,0,n)
#define RFOR(i,l,r) for(ll i=r-1;i>=l;i--)
#define RREP(i,n) RFOR(i,0,n)
#define ALL(x) x.begin(),x.end()
#define P pair<ll,ll>
#define F first
#define S second
#define BS(A,x) binary_search(ALL(A),x)
#define LB(A,x) (ll)(lower_bound(ALL(A),x)-A.begin())
#define UB(A,x) (ll)(upper_bound(ALL(A),x)-A.begin())
#define COU(A,x) (UB(A,x)-LB(A,x))
template<typename T>using min_priority_queue=priority_queue<T,vector<T>,greater<T>>;
using mint=modint1000000007;
//using mint=modint998244353;
void chmax(ll&a,ll b){a=max(a,b);}
void chmin(ll&a,ll b){a=min(a,b);}
int main(){
  ll N,M;cin>>N>>M;
  vector<ll>A(N);REP(i,N)cin>>A[i];
  ll l=0,r=1e18;
  while(l!=r){
    ll m=(l+r+1)/2;
    auto B=A;
    bool ok=1;
    REP(i,N){
      if(B[i]<m){ok=0;break;}
      else B[i+1]+=B[i]-m;
    }
    if(ok)l=m;else r=m-1;
  }
  cout<<l/M<<endl;
  return 0;
}