/in/foo.cc: In function 'int mian()':
/in/foo.cc:12:2: error: expected ';' before 'scanf'
  scanf("%d%d-%d%d",&a,&b,&c,&d);
  ^~~~~
/in/foo.cc:12:32: warning: statement is a reference, not call, to function 'scanf' [-Waddress]
  scanf("%d%d-%d%d",&a,&b,&c,&d);
                                ^
/in/foo.cc:12:32: warning: statement has no effect [-Wunused-value]
/in/foo.cc:14:18: error: lvalue required as left operand of assignment
  int fenzi=a*d=b*c;
                  ^
/in/foo.cc:33:1: warning: no return statement in function returning non-void [-Wreturn-type]
 }
 ^