foo.cc: In function 'int main()':
foo.cc:9:36: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
    if(fs[j]<fs[j+1]||fs[j]==fs[j+1]&&xs[j]>xs[j+1]){ 
                      ~~~~~~~~~~~~~~^~~~~~~~~~~~~~~
foo.cc:4:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d %d",&n,&m);
  ~~~~~^~~~~~~~~~~~~~~
foo.cc:6:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d %d",&xs[i],&fs[i]);
  ~~~~~^~~~~~~~~~~~~~~~~~~~~~~

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