foo.cc: In function ‘void selectsort()’:
foo.cc:10:49: warning: suggest parentheses around ‘&&’ within ‘||’ [-Wparentheses]
   10 |                         if(a[j]<a[i]||a[j]==a[i]&&b[j]>b[i]){
      |                                       ~~~~~~~~~~^~~~~~~~~~~
foo.cc:8:21: warning: unused variable ‘imin’ [-Wunused-variable]
    8 |                 int imin=i;
      |                     ^~~~