View Compilation Error

0_0_37733246_1861.cpp: In function 'std::vector<std::pair<int, int> > merge(std::vector<std::pair<int, int> >&)':
0_0_37733246_1861.cpp:77:14: error: expected unqualified-id before '[' token
         auto [x, y] = a[i];
              ^
0_0_37733246_1861.cpp:81:20: error: 'x' was not declared in this scope
         else */if (x > res.back().second) {
                    ^
0_0_37733246_1861.cpp:82:23: error: 'y' was not declared in this scope
             res.eb(x, y);
                       ^
0_0_37733246_1861.cpp:84:56: error: 'y' was not declared in this scope
             res.back().second = max(res.back().second, y);
                                                        ^