foo.cc: In function 'void dfs(int, int)':
foo.cc:8:9: warning: unused variable 'i' [-Wunused-variable]
    8 |     int i,nx,ny;
      |         ^
foo.cc: In function 'int main()':
foo.cc:26:9: warning: this 'for' clause does not guard... [-Wmisleading-indentation]
   26 |         for(int i=1;i<=n;i++)
      |         ^~~
foo.cc:32:17: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'for'
   32 |                 cout<<21780;
      |                 ^~~~

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