View Compilation Error

0_0_39207982_28062.cpp: In function 'int dfs(int, int)':
0_0_39207982_28062.cpp:16:38: error: 'res' was not declared in this scope
   16 |                 if(dfs(xx,yy)==false)res=0;
      |                                      ^~~
0_0_39207982_28062.cpp:18:35: error: 'res' was not declared in this scope
   18 |         if(x==1||x==n||y==1||y==m)res=0;
      |                                   ^~~
0_0_39207982_28062.cpp:19:16: error: 'res' was not declared in this scope
   19 |         return res;
      |                ^~~