/in/foo.cc: In function 'int what(int*)':
/in/foo.cc:18:1: warning: no return statement in function returning non-void [-Wreturn-type]
 }
 ^
/in/foo.cc: In function 'bool cmp(person, person)':
/in/foo.cc:20:16: warning: self-comparison always evaluates to false [-Wtautological-compare]
  return m.x*m.y<m.x*m.y;
         ~~~~~~~^~~~~~~~
/in/foo.cc: In function 'void mult(int*, int)':
/in/foo.cc:48:28: warning: left operand of comma operator has no effect [-Wunused-value]
  for(int i=10000,j=a1[0]; i>=1,j>=1; i--,j--)
                           ~^~~
/in/foo.cc: In function 'bool check(int*, int*)':
/in/foo.cc:29:1: warning: control reaches end of non-void function [-Wreturn-type]
 }
 ^