#include <bits/stdc++.h>
using namespace std;
void solve(){
    int n;
    cin>>n;
    int x;
    cin>>x;
    int ans=0;
    vector<pair<bool,int>> help;
    help.resize(n+1,{0,0});
    int tol=n+1;
    if (x!=0){
        tol=x;
        ans+=n-abs((0-x)%n);
    }
    int rs=ans;
    bool streak=false;
    int cnt=0;
    int j=0;
    for (int i=1; i<n;i++){
        int kulcs;
        cin>>kulcs;
        kulcs+=rs;
        kulcs%=n;
        help[kulcs]={true,rs};
        if (streak){
            j++;
            if (j==cnt) streak=false;
        }
        else{
            if (!help[i].first && tol>i){
                ans++;
                rs++;
            }
            if(help[i].first){
                streak=true;
                cnt=rs-help[i].second;
                j=0;
            }
        }
    }
    cout<<ans;

}
int main()
{
    int t=1;
    //cin>>t;
    while (t--) solve();
}