#include <bits/stdc++.h>

using namespace std;
class InParser {
private:
    FILE *fin;
    char *buff;
    int sp;

    char read_ch() {
        ++sp;
        if (sp == 4096) {
            sp = 0;
            fread(buff, 1, 4096, fin);
        }
        return buff[sp];
    }

public:
    InParser(const char* nume) {
        fin = fopen(nume, "r");
        buff = new char[4096]();
        sp = 4095;
    }

    InParser& operator >> (int &n) {
        char c;
        while (!isdigit(c = read_ch()) && c != '-');
        int sgn = 1;
        if (c == '-') {
            n = 0;
            sgn = -1;
        } else {
            n = c - '0';
        }
        while (isdigit(c = read_ch())) {
            n = 10 * n + c - '0';
        }
        n *= sgn;
        return *this;
    }

    InParser& operator >> (long long &n) {
        char c;
        n = 0;
        while (!isdigit(c = read_ch()) && c != '-');
        long long sgn = 1;
        if (c == '-') {
            n = 0;
            sgn = -1;
        } else {
            n = c - '0';
        }
        while (isdigit(c = read_ch())) {
            n = 10 * n + c - '0';
        }
        n *= sgn;
        return *this;
    }
};

class OutParser {
private:
    FILE *fout;
    char *buff;
    int sp;

    void write_ch(char ch) {
        if (sp == 50000) {
            fwrite(buff, 1, 50000, fout);
            sp = 0;
            buff[sp++] = ch;
        } else {
            buff[sp++] = ch;
        }
    }


public:
    OutParser(const char* name) {
        fout = fopen(name, "w");
        buff = new char[50000]();
        sp = 0;
    }
    ~OutParser() {
        fwrite(buff, 1, sp, fout);
        fclose(fout);
    }

    OutParser& operator << (int vu32) {
        if (vu32 <= 9) {
            write_ch(vu32 + '0');
        } else {
            (*this) << (vu32 / 10);
            write_ch(vu32 % 10 + '0');
        }
        return *this;
    }

    OutParser& operator << (long long vu64) {
        if (vu64 <= 9) {
            write_ch(vu64 + '0');
        } else {
            (*this) << (vu64 / 10);
            write_ch(vu64 % 10 + '0');
        }
        return *this;
    }

    OutParser& operator << (char ch) {
        write_ch(ch);
        return *this;
    }
    OutParser& operator << (const char *ch) {
        while (*ch) {
            write_ch(*ch);
            ++ch;
        }
        return *this;
    }
};
InParser f("divprim.in");
OutParser g("divprim.out");
int T,k,N;
bitset <1000005> V;
pair <int,int> Prim[1000005],Nrk[8];
bool Compare(const pair<int,int> &a,const pair<int,int> &b)
{
    if(a.second==b.second)
        return a.first<b.first;
    return a.second<b.second;
}
int main()
{
    for(int i=1; i<=500000; i++)
        Prim[i].first=i;
    for(int i=2; i<=500000; (i==2?i++:i+=2))
        if(!V[i])
            for(int j=1; i*j<=500000; j++)
                V[i*j]=true,Prim[i*j].second++;
    sort(Prim+1,Prim+500001,Compare);
    int x=0,y=1,cnt=0;
    for(int i=1;i<=500000;i++)
       if(cnt!=Prim[i].second)
        Nrk[cnt].first=y,Nrk[cnt].second=i-1,y=i,cnt++;
    Nrk[cnt].first=y,Nrk[cnt].second=500000;
    f>>T;
    while(T--)
    {
       f>>N>>k;
       int st=Nrk[k].first,dr=Nrk[k].second,ans=0;
       while(st<=dr)
       {
           int mi=(st+dr)>>1;
           if(Prim[mi].first<=N)
            ans=Prim[mi].first,st=mi+1;
           else dr=mi-1;
       }
       g<<ans<<'\n';
    }
    return 0;
}