What is the output of this given program?

#include iostream
#include map
using namespace std;
int main ()
{
   try 
{
     mapchar, int mymap;
     mapchar, int :: iterator it;
     mymap['a'] = 20;
     mymap['b'] = 40;
     mymap['c'] = 60;
     mymap['d'] = 80;
     it = mymap.find('b');
     mymap.erase (it);
     mymap.erase (mymap.find('d'));
     cout  mymap.find('a') - second  '\n';
}
     catch (...) 
{
     cout  "Unknown exception: "  endl;
}
     return 0;
}