/in/foo.cc: In function 'int main()':
/in/foo.cc:11:31: warning: left operand of comma operator has no effect [-Wunused-value]
     for(i=1;i<=n-1;i++) a[i+1]>=a[i],d=d+1;//特判:1~3组数据 
                         ~~~~~~^~~~~~
/in/foo.cc:5:49: warning: 'd' may be used uninitialized in this function [-Wmaybe-uninitialized]
  register int i,r,l,a[500001],s[500001],n,sum,m,d,seat;
                                                 ^
/in/foo.cc:5:51: warning: 'seat' may be used uninitialized in this function [-Wmaybe-uninitialized]
  register int i,r,l,a[500001],s[500001],n,sum,m,d,seat;
                                                   ^~~~