#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef double db;
#define int long long
const int N=1e5+5;
const double eps=1e-10;
const int mod=1e9+7;
#define endl '\n'
struct node{
    int first,second;
    inline bool operator<(const node &x)const{
        return second>x.second;
    }
};
void solve() {
    int n,m;
    cin>>n>>m;
    vector<int>a(n+5),vis(n+5);
    for(int i=0;i<n;i++){
        cin>>a[i];
    }
    priority_queue<node>q;
    int ans=n+5;
    int cnt=1;
    q.push({0,0});
    while(!q.empty()) {
        auto y = q.top();
        q.pop();
        if(vis[y.first])continue;
        vis[y.first]=1;
        if (y.second >= ans)continue;
        int p = a[y.first];
        if ((y.first + p) % n > m) {
            ans = min(ans, n - ((y.first + p) % n) + m + 1 + y.second);
        } else {
            ans = min(ans, m - ((y.first + p) % n) + 1 + y.second);
        }
        int l = 1;
        while ((y.first + p) % n !=m) {
            q.push({(y.first + p) % n, y.second + l});
            l++;
            p++;
            p %= n;
            if (y.second + l > ans)break;
            cnt++;
        }
    }
    cout<<ans<<endl;
}
signed main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);cout.tie(nullptr);
    //cout<<fixed<<setprecision(12);
    int T=1;
    //  cin>>T;
    while(T--) solve();
    return 0;
}