/in/foo.cc: In function 'int main()':
/in/foo.cc:35:15: warning: array subscript has type 'char' [-Wchar-subscripts]
     if (vis[ch]) err=1; vis[ch]=1;
               ^
/in/foo.cc:35:5: warning: this 'if' clause does not guard... [-Wmisleading-indentation]
     if (vis[ch]) err=1; vis[ch]=1;
     ^~
/in/foo.cc:35:25: note: ...this statement, but the latter is misleadingly indented as if it is guarded by the 'if'
     if (vis[ch]) err=1; vis[ch]=1;
                         ^~~
/in/foo.cc:35:31: warning: array subscript has type 'char' [-Wchar-subscripts]
     if (vis[ch]) err=1; vis[ch]=1;
                               ^
/in/foo.cc:41:21: warning: array subscript has type 'char' [-Wchar-subscripts]
     vis[stack[top--]]=0;
                     ^
/in/foo.cc:47:22: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
    if (ans==x||tot==1&&x==0) printf("Yes\n"); else printf("No\n");
                ~~~~~~^~~~~~
/in/foo.cc:22:9: warning: unused variable 'cnt' [-Wunused-variable]
   int L,cnt=0,ans=0; top=0;
         ^~~