View Compilation Error

0_0_22022523_11466.cpp: In function 'int main()':
0_0_22022523_11466.cpp:61:6: error: 'top' was not declared in this scope
      top++;
      ^
0_0_22022523_11466.cpp:78:6: error: 'top' was not declared in this scope
   if(top>50000) top/=0;
      ^
0_0_22022523_11466.cpp:79:3: error: 'top' was not declared in this scope
   top=0;
   ^