View Compilation Error

0_0_17653634_27982.cpp: In function 'int dfs(int, int, int, int)':
0_0_17653634_27982.cpp:19:14: error: 't2' was not declared in this scope
     int t1 = t2 = t3 = t4 = 0;
              ^
0_0_17653634_27982.cpp:19:19: error: 't3' was not declared in this scope
     int t1 = t2 = t3 = t4 = 0;
                   ^
0_0_17653634_27982.cpp:19:24: error: 't4' was not declared in this scope
     int t1 = t2 = t3 = t4 = 0;
                        ^