foo.cc: In function 'int calf(std::vector<std::vector<int> >&, int, int)':
foo.cc:22:1: warning: control reaches end of non-void function [-Wreturn-type]
   22 | }
      | ^
foo.cc: In function 'int cals(std::vector<std::vector<int> >&, int, int)':
foo.cc:36:1: warning: control reaches end of non-void function [-Wreturn-type]
   36 | }
      | ^

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