/in/foo.cc: In function 'bool p(int)':
/in/foo.cc:7:19: error: 'a' was not declared in this scope
  for(int i=1;i*i<=a;i++)
                   ^
/in/foo.cc: In function 'int main()':
/in/foo.cc:18:23: error: lvalue required as left operand of assignment
      if(p(i)==true||i=1)
                       ^