/in/foo.cc: In function 'int work(int, int, int)':
/in/foo.cc:29:3: warning: this 'if' clause does not guard... [-Wmisleading-indentation]
   if(l==lim) l++; if(r==lim) r--;
   ^~
/in/foo.cc:29:19: note: ...this statement, but the latter is misleadingly indented as if it is guarded by the 'if'
   if(l==lim) l++; if(r==lim) r--;
                   ^~
/in/foo.cc: In function 'int dfs(int, int, int)':
/in/foo.cc:56:13: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
    int mid=l+r>>1;
            ~^~
/in/foo.cc:60:12: warning: suggest parentheses around assignment used as truth value [-Wparentheses]
   if(ans=-1) return 0;
            ^
/in/foo.cc: In function 'int main()':
/in/foo.cc:84:12: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   int mid=l+r>>1;
           ~^~