foo.cc: In function 'int main()':
foo.cc:10:23: warning: unused variable 'b' [-Wunused-variable]
     int i,n,a[100001],b,m=0;
                       ^
foo.cc:11:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d",&n);
     ~~~~~^~~~~~~~~
foo.cc:15:30: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
             scanf("%d",&a[i]),m++;
             ~~~~~~~~~~~~~~~~~^~~~

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