/in/foo.cc: In function 'int fz(int)':
/in/foo.cc:8:25: error: invalid operands of types '__gnu_cxx::__promote_2<int, int, double, double>::__type {aka double}' and 'int' to binary 'operator%'
  if(y%2==1)t*=pow(t,b)*b%k;
               ~~~~~~~~~~^~
/in/foo.cc:9:13: error: invalid operands of types '__gnu_cxx::__promote_2<int, int, double, double>::__type {aka double}' and 'int' to binary 'operator%'
  t*=pow(t,b)%k;
     ~~~~~~~~^~