foo.cc: In function 'int main()':
foo.cc:20:10: warning: unused variable 'm' [-Wunused-variable]
   20 |  int c,d,m,n,a[100],k;
      |          ^
foo.cc:20:12: warning: unused variable 'n' [-Wunused-variable]
   20 |  int c,d,m,n,a[100],k;
      |            ^
foo.cc:20:14: warning: unused variable 'a' [-Wunused-variable]
   20 |  int c,d,m,n,a[100],k;
      |              ^

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