# include <bits/stdc++.h>
using namespace std;
ifstream fi("reguli.in");
ofstream fo("reguli.out");
const int nmax = 5e5 + 5;
int v[nmax];
int s[nmax];
int main(void)
{
    int n,x,y;
    fi>>n>>y;
    for (int i=1;i<n;++i) fi>>x,s[i]=y-x,y=x;
    for (int i=2,k=0;i<n;++i)
    {
        while (k && s[k+1] != s[i]) k = v[k];
        k += (s[k+1] == s[i]);v[i] = k;
    }
    return fo << (n - v[n]) << '\n',0;
}