/in/foo.cc: In function 'int main()':
/in/foo.cc:28:5: error: 'unordered_map' was not declared in this scope
     unordered_map<int, long long> map;
     ^~~~~~~~~~~~~
/in/foo.cc:28:19: error: expected primary-expression before 'int'
     unordered_map<int, long long> map;
                   ^~~
/in/foo.cc:39:16: error: missing template arguments before '.' token
         if (map.contains(remainder)) {
                ^
/in/foo.cc:40:33: error: missing template arguments before '[' token
             total = (total + map[remainder]) % mod;
                                 ^
/in/foo.cc:41:16: error: missing template arguments before '[' token
             map[remainder] += 1;
                ^
/in/foo.cc:43:16: error: missing template arguments before '[' token
             map[remainder] = 1;
                ^