/in/foo.cc: In function 'int main()':
/in/foo.cc:20:5: error: 'unordered_map' was not declared in this scope
     unordered_map<int, int> countMap;
     ^~~~~~~~~~~~~
/in/foo.cc:20:19: error: expected primary-expression before 'int'
     unordered_map<int, int> countMap;
                   ^~~
/in/foo.cc:26:30: error: 'countMap' was not declared in this scope
         for (const auto& p : countMap) {
                              ^~~~~~~~
/in/foo.cc:34:13: error: 'countMap' was not declared in this scope
             countMap[vec[i][0]]++;
             ^~~~~~~~
/in/foo.cc:36:13: error: 'countMap' was not declared in this scope
             countMap[vec[i][0]] = 1;
             ^~~~~~~~
/in/foo.cc:42:26: error: 'countMap' was not declared in this scope
     for (const auto& p : countMap) {
                          ^~~~~~~~