View Compilation Error

0_0_27759940_2393.cpp: In function 'bool trav(int, int)':
0_0_27759940_2393.cpp:19:6: error: 'mrk' was not declared in this scope
   if(mrk[fst]) return 0;
      ^
0_0_27759940_2393.cpp:20:3: error: 'mrk' was not declared in this scope
   mrk[fst]=1;
   ^
0_0_27759940_2393.cpp: In function 'bool calc()':
0_0_27759940_2393.cpp:53:9: error: 'mrk' was not declared in this scope
  memset(mrk,0,sizeof(mrk));
         ^