/in/foo.cc: In function 'int main()':
/in/foo.cc:7:9: warning: comparison of constant '86399' with boolean expression is always true [-Wbool-compare]
     0<=a<=86399;
     ~~~~^~~~~~~
/in/foo.cc:7:6: warning: comparisons like 'X<=Y<=Z' do not have their mathematical meaning [-Wparentheses]
     0<=a<=86399;
     ~^~~
/in/foo.cc:7:9: warning: statement has no effect [-Wunused-value]
     0<=a<=86399;
     ~~~~^~~~~~~