#include <bits/stdc++.h>
#pragma GCC target("avx2")
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
using namespace std;
using ll = long long;
const ll mod = 998244353;
#define fi first
#define se second
#define rep(i,n) for(ll i=0;i<n;i++)
#define all(x) x.begin(),x.end()
#define faster ios::sync_with_stdio(false);cin.tie(nullptr)

int main() {
    ll N;
    cin >> N;
    vector<ll> A(N);
    rep(i,N) cin >> A[i];
    ll ans=0;
    rep(i,N){
        if(A[i]!=A[0]) break;
        ans++;
    }
    for(ll i=N-1;i>=0;i--){
        if(A[i]!=A[N-1]) break;
        ans++;
    }
    if(ans==N*2) ans=N+1;
    cout << ans-1 << endl;
    return 0;
}