Correct size of bit sets

code/BitSet.cpp

@@ -2,7 +2,7 @@
 typedef long long T;
 const int MAXN = 5000;
 const int BITS = (sizeof(T)*8);
-const int SIZE = ((MAXN+BITS)/BITS); // size of arrays
+const int SIZE = ((MAXN+BITS-1)/BITS); // size of arrays
 void clear(T a[]) {
   memset(a, 0, sizeof(T[SIZE]));
 }