#include<bits/stdc++.h>
using namespace std;

#define ll long long
#define cpy(a,b) copy(begin(a),end(a),begin(b))
#define ld long double
#define dot(x) fixed<<setprecision(x)
#define foru(a,b,c) for(ll a=b;a<=c;a++)

ll t,n,k,a[200005];

int main(){
    freopen("ntarsis_set.in" ,"r",stdin );
    freopen("ntarsis_set.out","w",stdout);
    ios::sync_with_stdio(false);
    cin.tie(NULL);cout.tie(NULL);
    cin>>n>>k;
    foru(i,1,n){
        ll x;
        cin>>x;
        a[i]=x-i;
    }
    ll ans=1;
    foru(i,1,k){
        auto it=lower_bound(a+1,a+n+1,ans);
        ll cnt=distance(a+1, it);
        ans+=cnt;
    }
    cout<<ans<<endl;
    return 0;
}