foo.cc: In function 'void dfs(int, int)':
foo.cc:8:24: error: return-statement with a value, in function returning 'void' [-fpermissive]
    8 |                 return ans;
      |                        ^~~
foo.cc: In function 'int main()':
foo.cc:45:15: error: 'ret' was not declared in this scope
   45 |         cout<<ret;
      |               ^~~

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