/in/foo.cc: In function 'bool chk(int)':
/in/foo.cc:14:15: warning: suggest parentheses around '+' inside '<<' [-Wparentheses]
   memcpy(c,a,n+1<<2);
              ~^~
/in/foo.cc:14:20: error: 'memcpy' was not declared in this scope
   memcpy(c,a,n+1<<2);
                    ^
/in/foo.cc: In function 'int main()':
/in/foo.cc:42:18: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
  for (int mid=l+r+1>>1;l<r;mid=l+r+1>>1) {
               ~~~^~
/in/foo.cc:42:35: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
  for (int mid=l+r+1>>1;l<r;mid=l+r+1>>1) {
                                ~~~^~