View Compilation Error

0_0_28170891_15548.cpp: In function 'void dfs(int, int)':
0_0_28170891_15548.cpp:5:14: error: 'ans' was not declared in this scope
     if(l==0){ans = min(ans,r);return;}
              ^
0_0_28170891_15548.cpp:6:19: error: 'ans' was not declared in this scope
     if(l+l < r+1||ans != 0x7f7f7f7f)return;
                   ^