View Compilation Error

0_0_14043263_23874.cpp: In function 'void BFS(int)':
0_0_14043263_23874.cpp:75:36: error: 'k' was not declared in this scope
  if (!worked[mark[v0][i]] && dd[Qs[k][0] + Qs[k][1] - v0] == 2) {
                                    ^
0_0_14043263_23874.cpp:76:10: error: redeclaration of 'int k'
      int k = mark[v0][i];
          ^
0_0_14043263_23874.cpp:75:36: note: '<typeprefixerror>k' previously declared here
  if (!worked[mark[v0][i]] && dd[Qs[k][0] + Qs[k][1] - v0] == 2) {
                                    ^