app crash when there's more than 3000 entries in std::map ?

Hi everyone

I have this strange behaviour happening with this code which I can't
explain. On my computer when I set nt with a value greater than 3000
it crashes. Is there a max number of keys I can use with a std::map ?

thanks a lot

#include <vector>
#include <iostream>
#include <map>

#include <string>

int main()
{
    float t = clock();
    int nt = 3000;
#if 1
    hash_map<std::string, int, hash<std::string> > mymap;
    for ( int i = 0; i < nt; ++i )
    {
        string tmp = "test" + i;
        mymap[ tmp ] = i;
    }
    for ( int i = 0; i < 10e5; ++i )
    {
        int a = (int)(drand48() * nt);
        string tmp = "test" + a;
        hash_map<std::string, int, hash<std::string> >::iterator it =
mymap.find( tmp );
        if ( it != mymap.end() )
        {
        }
        else
        {
            printf("not found\n");
        }
    }
    unsigned max_size = mymap.max_size();
    printf("%d\n", max_size );

#else
    std::map<std::string, int> mymap;
    for ( int i = 0; i < nt; ++i )
    {
        string tmp = "test" + i;
        mymap[ tmp ] = i;
    }
    for ( int i = 0; i < 10e5; ++i )
    {
        int a = (int)(drand48() * nt);
        string tmp = "test" + a;
        std::map<std::string, int>::iterator it = mymap.find( tmp );
        if ( it != mymap.end() )
        {
        }
        else
        {
            printf("not found\n");
        }
    }

    unsigned max_size = mymap.max_size();
    printf("%d\n", max_size );

#endif
    printf("time %f\n", (clock() - t ) / float( CLOCKS_PER_SEC ) );

    return 0;
}

#endif