运行 ID: 43475

Main.cc: In function ‘int main()’:
Main.cc:5:9: warning: comparison of constant ‘1000’ with boolean expression is always true [-Wbool-compare]
     1<=n<=1000;
     ~~~~^~~~~~
Main.cc:5:6: warning: comparisons like ‘X<=Y<=Z’ do not have their mathematical meaning [-Wparentheses]
     1<=n<=1000;
     ~^~~
Main.cc:5:9: warning: statement has no effect [-Wunused-value]
     1<=n<=1000;
     ~~~~^~~~~~
Main.cc:7:6: error: ‘a’ was not declared in this scope
      a++  
      ^