Red Huang

/\*  
 \* GCA : "Computer is artificial subject absolutely,Math is God"  
 \*/  
#include <iostream>  
#include <cstdio>  
#include <cstring>  
#include <algorithm>  
#include <cmath>  
#include <climits>  
#include <vector>  
#include <set>  
#include <map>  
#include <queue>  
#include <cctype>  
#include <utility>  
#include <ctime>  
using namespace std;  
#ifdef DEBUG  
#define VAR(a,b) \_\_typeof(b) a=(b)  
#define debug(...) printf("DEBUG: "),printf(\_\_VA\_ARGS\_\_)  
#else  
#define VAR(a,b) decltype(b) a=(b)  
#define debug(...)  
#endif  
typedef unsigned int uint;  
typedef long long int Int;  
typedef unsigned long long int UInt;  
#define Set(a,s) memset(a,s,sizeof(a))  
#define Pln() printf("\\n")  
#define For(i,x)for(int i=0;i<x;i++)  
#define CON(x,y) x##y  
#define M ${MAX\_LIMITS}  
#define PB push\_back  
#define oo INT\_MAX  
#define FOR(a,b) for(VAR(a,(b).begin());a!=(b).end();++a)  
#define eps 1e-9  
#define X first  
#define Y second  
inline bool xdy(double x,double y){return x>y+eps;}  
inline bool xddy(double x,double y){return x>y-eps;}  
inline bool xcy(double x,double y){return x<y-eps;}  
inline bool xcdy(double x,double y){return x<y+eps;}  
const Int mod=1000000007;  
  
  
class ClapLight {  
    bool check(vector<int\> v,int t){  
        for(int i=0;i<v.size()-3;i++){  
            if(v\[i\]<t&&v\[i+1\]>=t&&v\[i+2\]>=t&&v\[i+3\]<t){  
                return false;  
            }  
        }  
        return true;  
    }  
    public: int threshold(vector<int\> background) {  
        vector<int\> sor=background;  
        sort(sor.begin(),sor.end());  
        int cen=(sor.size())/2;  
        int from=sor\[cen\]+1;  
        int to=sor\[sor.size()-1\]+1;  
        if(from>to)to=from;  
        for(int i=from;i<=to;i++){  
            if(check(background,i)){  
                return i;  
            }  
        }  
        return -1;  
    }  
  
  
};