foo.cc: In function 'int main()':
foo.cc:9:13: warning: comparison of constant '1000' with boolean expression is always true [-Wbool-compare]
    if(x,1<=x<=1000)
         ~~~~^~~~~~
foo.cc:9:10: warning: comparisons like 'X<=Y<=Z' do not have their mathematical meaning [-Wparentheses]
    if(x,1<=x<=1000)
         ~^~~
foo.cc:9:15: warning: left operand of comma operator has no effect [-Wunused-value]
    if(x,1<=x<=1000)
               ^~~~

[Hydro](https://hydro.ac)提供评测服务