Help somebody!!
Why my code has WA6..or GIVE SOME TESTS, please))

#include<iostream>
#include<vector>
#include<cmath>
using namespace std;

vector<int>easy_numbers(0);

int next_number(int numb_of_numb)
{
        int step=easy_numbers.size()-1;
        int curr_number=easy_numbers[step];
        while(step+1<numb_of_numb)
        {
                while(1)
                {
                        curr_number++;
                        int sq_root=sqrt(static_cast<double>(curr_number))+1;
                        int buf_step;
                        buf_step=0;
                        while(easy_numbers[buf_step]<sq_root)
                                if (curr_number%easy_numbers[buf_step++]!=0) continue;
                                else goto g1;
                        break;
                        g1:
                }
                easy_numbers.push_back(curr_number);
                step++;
        }
        return curr_number;
}

int main()
{
        int K;
        int L=-1;
        cin >> K;
        if (K==4) {cout << 3; exit(0);}
        easy_numbers.push_back(3);
        int buf=0;
        while((easy_numbers[buf]*easy_numbers[buf])<=K)
        next_number(++buf);
        for (int i=0;i<easy_numbers.size();i++)
        {
                if (K%easy_numbers[i]==0) {L=easy_numbers[i]-1; break;}

        }
        if (L==-1 && K%2==0) {L=K/2-1; cout << L;
        exit(0);}
        if (L==-1) {L=K-1; cout << L;
        exit(0);}
        cout << L;
        return 0;
}