View Compilation Error

0_0_28966281_9834.cpp:11:1: error: 'bitset' does not name a type
 bitset<N> f[N];
 ^
0_0_28966281_9834.cpp: In function 'int main()':
0_0_28966281_9834.cpp:32:13: error: 'f' was not declared in this scope
             f[i].reset();
             ^
0_0_28966281_9834.cpp:41:26: error: 'f' was not declared in this scope
                 int w = (f[i] & f[j]).count();
                          ^