foo.cc: In function 'int main()':
foo.cc:5:14: warning: comparisons like 'X<=Y<=Z' do not have their mathematical meaning [-Wparentheses]
 {   int a,b(0<a<b<10000),k(0<=k<=9); cin>>a>>b>>k;
             ~^~
foo.cc:5:18: warning: comparison of constant '10000' with boolean expression is always true [-Wbool-compare]
 {   int a,b(0<a<b<10000),k(0<=k<=9); cin>>a>>b>>k;
             ~~~~~^~~~~~
foo.cc:5:16: warning: comparisons like 'X<=Y<=Z' do not have their mathematical meaning [-Wparentheses]
 {   int a,b(0<a<b<10000),k(0<=k<=9); cin>>a>>b>>k;
             ~~~^~
foo.cc:5:32: warning: comparison of constant '9' with boolean expression is always true [-Wbool-compare]
 {   int a,b(0<a<b<10000),k(0<=k<=9); cin>>a>>b>>k;
                            ~~~~^~~
foo.cc:5:29: warning: comparisons like 'X<=Y<=Z' do not have their mathematical meaning [-Wparentheses]
 {   int a,b(0<a<b<10000),k(0<=k<=9); cin>>a>>b>>k;
                            ~^~~