foo.cc: In function 'int jidazhi(int (*)[500], int, int)':
foo.cc:5:16: warning: unused variable 'flag1' [-Wunused-variable]
    5 |  int flag = 0, flag1 = 0;
      |                ^~~~~
foo.cc: In function 'int main()':
foo.cc:49:9: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
   49 |  freopen("data.txt", "r", stdin);
      |  ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~

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