foo.cc: In function 'int main()':
foo.cc:5:19: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
    5 |     int n,m; scanf("%d%d",&n,&m);
      |              ~~~~~^~~~~~~~~~~~~~
foo.cc:7:32: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
    7 |     for(int i=1;i<=n;i++) scanf("%d", &a[i]);
      |                           ~~~~~^~~~~~~~~~~~~

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