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//==================================================================//
// Name        : flash7even                                         //
// Author      : Tarango Khan                                       //
// Codeforces  : flash_7                                            //
// Topcoder    : flash_7                                            //
// Hackerrank  : flash_7                                            //
// Email       : [email protected]                            //
// Facebook    : flash7even                                         //
//==================================================================//

//==================================================================//
#include <bits/stdc++.h>                                            //
using namespace std;                                                //
#define read(nm)        freopen(nm, "r", stdin)                     //
#define write(nm)       freopen(nm, "w", stdout)                    //
#define pb              push_back                                   //
#define MP              make_pair                                   //
#define ff              first                                       //
#define ss              second                                      //
#define FABS(x)         ((x)+eps<0?-(x):(x))                        //
#define POPCOUNT        __builtin_popcountll                        //
#define RIGHTMOST       __builtin_ctzll                             //
#define LEFTMOST(x)     (63-__builtin_clzll((x)))                   //
#define NUMDIGIT(x,y)   (((int)(log10((x))/log10((y))))+1)          //
#define SQ(x)           ((x)*(x))                                   //
#define pf              printf                                      //
#define sf              scanf                                       //
#define phl             printf("hello\n")                           //
#define SZ(x)           ((int)(x).size())                           //
#define mems(x,v)       memset(x,v,sizeof(x))                       //
#define CLR(x,y)        memset(x,y,sizeof(x))                       //
#define ALL(x)          (x).begin(),(x).end()                       //
#define NORM(x)         if(x>=mod)x-=mod;                           //
#define MOD(x,y)        (((x)*(y))%mod)                             //
#define fills(v,n)      fill(v.begin(), v.end(), n)                 //
#define LL              long long                                   //
#define LLU             long long unsigned int                      //
#define vlong           long long                                   //
#define uvlong          unsigned long long                          //
#define debug1(v1)      cout<<"1@ Debug Val 1 = "<<v1<<endl;        //
#define debug2(v2)      cout<<"   2@ Debug Num 2 = "<<v2<<endl;     //
#define debug3(v3)      cout<<"      3@ Debug Res 3 = "<<v3<<endl;  //
#define UB(v,a)         upper_bound(v.begin(),v.end(),a)-v.begin()  //
#define LB(v,a)         lower_bound(v.begin(),v.end(),a)-v.begin()  //
#define fast_cin ios_base::sync_with_stdio(false);cin.tie(NULL)     //
//==================================================================//

//==================================================================//
void make_unique(vector<int> &a){ sort(a.begin(), a.end());         //
     a.erase(unique(a.begin(), a.end()), a.end()); }                //
void printDouble(double f,int p){ cout << fixed;                    //
     cout << setprecision(p) << f <<endl; }                         //
int  Set(int N,int cur){ return N = N | (1<<cur); }                 //
int  Reset(int N,int cur){ return N = N & ~(1<<cur); }              //
bool Check(int N,int cur){ return (bool)(N & (1<<cur)); }           //
LL   GCD(LL a,LL b){ if(b == 0) return a; return GCD(b,a%b);}       //
LL   LCM(LL a,LL b){ return a*b/GCD(a,b);}                          //
LL   POW(LL a,LL p){ LL res = 1,x = a;while(p){if(p&1)              //
     res = (res*x); x = (x*x);p >>= 1;} return res;}                //
//==================================================================//

//==================================================================//
//int knightDir[8][2] = {{-2,1},{-1,2},{1,2},{2,1},                 //
//                      {2,-1},{-1,-2},{1,-2},{-2,-1}};             //
//int dir8[8][2]      = {{-1,0},{0,1},{1,0},{0,-1},                 //
//                      {-1,-1},{1,1},{1,-1},{-1,1}};               //
//int dir4[4][2]      = {{-1,0},{0,1},{1,0},{0,-1}};                //
//==================================================================//

#ifdef forthright48
     #include <ctime>
     clock_t tStart = clock();
     #define debug(args...) {dbg,args; cerr<<endl;}
     #define timeStamp printf("Exc Time: %.2fs\n",(double)(clock()-tStart)/CLOCKS_PER_SEC)
#else
     #define debug(args...)
     #define timeStamp
#endif

struct debugger{
    template<typename T> debugger& operator , (const T& v){
        cerr << v << " ";
        return *this;
    }
}dbg;

typedef pair <LL,LL> pll;
typedef vector<pll> vll;
typedef vector<LL> vl;

const LL inf = 2147383647;
const LL MOD = 1000000007;
const double pi = 2*acos(0.0);
const double eps = 1e-9;
#define Size 100005

//=======// Done With The Shortcut Stuffs! Now Let's Code! //=======//

int N;
int A[1000005];

int maxOccur(){
    if(N == 1) return 1;
    int res = 1,cnt = 1,i = 1;
    while(i<N){
        if(A[i] == A[i-1]){
            cnt++;
        }else{
            res = max(res,cnt);
            cnt = 1;
        }
        i++;
    }
    res = max(res,cnt);
    if(A[0] == A[N-1]){
        cnt = 2;
        i = 1;
        while(i<N){
            if(A[i] != A[i-1]) break;
            i++;
            cnt++;
        }
        i = N-2;
        while(i>=0){
            if(A[i] != A[i+1]) break;
            i--;
            cnt++;
        }
        res = max(res,cnt);
    }
    return res;
}

int main() {
    sf("%d",&N);
    for(int i = 0;i<N;i++){
        sf("%d",&A[i]);
    }
    int mxc = maxOccur();
    int res = mxc + (N-mxc)*2;
    cout << res << endl;
}