Problem with vector from STL

I'd like to write some program, where in some function there are addes
some elements to the container vector<int> sequences, which is empty
at start of the program. This is the code:

//------------------------------------------------------ code
--------------------------------------------------------------------
#include <iostream>
#include <cstdlib>
#include <vector>
using namespace std;

struct int4 {
   int a1,a4,a16,a64;
};

vector<int> sequences;
vector<int> bestBoard(4,0);
int MAX=0;

bool different(int x) {
   for (int i=0;i<sequences.capacity();i++)
      if (sequences.at(i)==x) return false;
   return true;
}

void checkBoard(int r1,int r2,int r3,int r4) {
   int A[4][4];

   A[0][0]=1
   A[0][1]=2
   A[0][2]=0
   A[0][3]=1
   //I set other A[i][j]

   vector<int> board(4);
   board.at(0)=r1;
   board.at(1)=r2;
   board.at(2)=r3;
   board.at(3)=r4;

   for (int i=0;i<4;i++)
   for (int j=0;j<4;j++)
   {
      cout<<"i="<<i<<" j="<<j<<" test------------------->"<<endl;
      //here more or less is produced error for i=1, j=3
      int x=i;
      int z=A[i][j];
      while (x>0) {
         x--;
         z=4*z+A[x][j];
         cout<<z<<endl;
         cout<<different(z)<<endl;
         cout<<sequences.capacity()<<endl;
         if (different(z)) sequences.push_back(z);
      }

   }
   if (sequences.capacity()>MAX) {
      MAX=sequences.capacity();
      bestBoard=board;
      cout<<"current MAX: "<<sequences.capacity()<<endl;
   }
}

int main() {
   int row1,row2,row3,row4;
   const int iterations=5000;

   for (int i=0;i<iterations;i++)
   {
       row1=rand()%256;
       row2=rand()%256;
       row3=rand()%256;
       row4=rand()%256;
       checkBoard(row1,row2,row3,row4);
   }

   system("pause");
   return 0;
}
//------------------------------------------------------ end code
----------------------------------------------------------------

and the program could be compiled without any problems, but when I try
to start it terminate in checkBoard in for loop for i=1,j=3 ... and I
don't know why and what I did wrong.

Please for help!!