foo.cc: In function 'bool check(int, int, std::vector<std::vector<int> >&)':
foo.cc:12:18: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
  if (si - 1 >= 0 && list[si - 1][sj] >= list[si][sj] || si - 1 < 0)
foo.cc:14:17: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
  if (si + 1 < n && list[si + 1][sj] >= list[si][sj] || si + 1 >= n)
foo.cc:16:18: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
  if (sj - 1 >= 0 && list[si][sj - 1] >= list[si][sj] || sj - 1 < 0)
foo.cc:18:17: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
  if (sj + 1 < m && list[si][sj + 1] >= list[si][sj] || sj + 1 >= m)
foo.cc: In function 'int solve(std::vector<std::vector<int> >&)':
foo.cc:65:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i = 0; i < list.size(); i++)
                  ~~^~~~~~~~~~~~~
foo.cc:66:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for (int j = 0; j < list[0].size(); j++)
                   ~~^~~~~~~~~~~~~~~~

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