/in/foo.cc: In function 'int main()':
/in/foo.cc:13:10: warning: comparisons like 'X<=Y<=Z' do not have their mathematical meaning [-Wparentheses]
      if(x<y<z)
         ~^~
/in/foo.cc:15:7: error: 'k' was not declared in this scope
       k++;//计算 升序数的个数 
       ^