foo.cc: In function 'std::vector<int> solve(std::vector<int>&, std::vector<int>&)':
foo.cc:10:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   10 |     for (int i = 0; i < a.size(); i++)
      |                     ~~^~~~~~~~~~
foo.cc: In function 'int main()':
foo.cc:34:12: error: missing template arguments before 'ans'
   34 |     vector ans = solve(a, b);
      |            ^~~
foo.cc:36:19: error: 'ans' was not declared in this scope; did you mean 'abs'?
   36 |     for (auto x : ans) cout << x << ' ';
      |                   ^~~
      |                   abs

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