View Compilation Error

0_0_35920529_22000.cpp: In function 'void tarjan(int, int)':
0_0_35920529_22000.cpp:45:22: error: 'root' was not declared in this scope
             if (x != root && dfn[x] <= low[to]) {
                      ^
0_0_35920529_22000.cpp:51:14: error: 'root' was not declared in this scope
     if (x == root && tot > 1) {
              ^