foo.cc: In function 'int count_7(int)':
foo.cc:9:9: warning: unused variable 'bt' [-Wunused-variable]
  int at,bt;
         ^~
foo.cc: In function 'int main()':
foo.cc:26:9: warning: statement has no effect [-Wunused-value]
  for (qt;qt<=wt;qt++)
         ^

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