#include <fstream>
#include <bitset>

using namespace std;

class InputReader
{
public:
    static const int BUFF_SIZE = 1 << 17;
    FILE *fin;
    int bp;
    char buff[BUFF_SIZE];
    InputReader (const char *file_name)
    {
        fin = fopen(file_name, "r");
        bp = BUFF_SIZE - 1;
    }
    void close()
    {
        fclose(fin);
    }
    void adv()
    {
        if (++bp == BUFF_SIZE)
        {
            fread(buff, sizeof(char), BUFF_SIZE, fin);
            bp = 0;
        }
    }
    InputReader& operator >> (int& num)
    {
        num = 0;
        while (isdigit(buff[bp]) == false)
            adv();
        while (isdigit(buff[bp]))
        {
            num = num * 10 + buff[bp] - '0';
            adv();
        }
        return *this;
    }
};

class ofbuffer
{
private:
    char* b_text;
    int b_capacity, b_size;
    FILE* file;

    inline void b_put_ch( char ch )
    {
        b_text[b_size ++] = ch;
        if ( b_size == b_capacity )
            b_flush();
    }

    void b_put_nr( int x )
    {
        if ( x > 0 )
        {
            b_put_nr( x / 10 );
            b_put_ch( '0' + x % 10 );
        }
    }

public:
    inline ofbuffer( char * path, int capacity = 16000 )
    {
        file = fopen( path, "w" );

        b_text = new char[capacity];
        b_capacity = capacity;
        b_size = 0;
    }

    inline ~ofbuffer()
    {
        if ( b_size != 0 )
            b_flush();
    }

    inline void b_flush( void )
    {
        fwrite( b_text, 1, b_size, file );
        b_size = 0;
    }

    inline ofbuffer &operator<<( int v )
    {
        if ( v == 0 )
            b_put_ch( '0' );
        else
            b_put_nr( v );
        return *this;
    }

    inline ofbuffer &operator<<( char v )
    {
        b_put_ch( v );
        return *this;
    }

    inline void close()
    {
        b_flush();
        fclose( file );
    }
};

InputReader fin("divprim.in");
ofbuffer fout("divprim.out");

const int MAXN = 1e6 + 5;

bitset < MAXN > ciur;
int P[MAXN >> 1],K;
int v[MAXN];

void sieve()
{
    ciur[0] = ciur[1] = 1;
    for (int i = 2; i < MAXN; ++i)
    {
        if (!ciur[i])
        {
            P[++K] = i;
            for (int j = (i << 1); j < MAXN; j += i)
            {
                ciur[j] = 1;
            }
        }
    }
}

int main()
{
    int t,i,j,x,k;
    sieve();
    for (i = 1; i <= K; ++i)
    {
        for (j = P[i]; j < MAXN; j += P[i])
        {
            ++v[j];
        }
    }
    fin >> t;
    while (t--)
    {
        fin >> x >> k;
        bool ok = 0;
        for (i = x - 1; i >= 2; --i)
        {
            if (v[i] == k)
            {
                fout << i << '\n';
                ok = 1;
                break;
            }
        }
        if (!ok) fout << 0 << '\n';
    }
    return 0;
}