View Compilation Error

0_0_23208039_14897.cpp:11:1: error: 'stack1' does not name a type
 stack1 <int> stack1_;
 ^
0_0_23208039_14897.cpp: In function 'void Tarjan(int)':
0_0_23208039_14897.cpp:19:5: error: 'stack1_' was not declared in this scope
     stack1_.push(u);
     ^