Language: C++

// 
const int maxn = 63;
LL F[maxn][2][2][2][2];

bool A[maxn], B[maxn];
LL solve(int n, int a1, int b1, int a2, int b2) {
	if (n == -1) return 1;
	LL &res = F[n][a1][b1][a2][b2];
	if (res != -1) return res;
	res = 0;
	int a11 = a1 ? A[n] : 0;
	int b11 = b1 ? B[n] : 1;
	int a22 = a2 ? A[n] : 0;
	int b22 = b2 ? B[n] : 1;
	// cout << n << " " << a11 << " " << b11 << " " << a22 << " " << b22 << endl;
	for (int i = a11; i <= b11; ++i) {
		for (int j = a22; j <= b22; ++j) {
			// cout << i << " " << j << endl;
			if (i > j) continue;
			// if (i && j) continue;
			LL t = solve(n - 1, a1 && i == a11, b1 && i == b11, a2 && j == a22, b2 && j == b22);
			t = t  % mod;
			res += t;
			//cout << n << ' ' << i << ' ' << j << " " << t << endl;

			res %= mod;
		}
	}

	return res;
}
int main(void)
{
	LL a, b; cin >> a >> b;
	LL ans = 0;
	for (int i = 62; i >= 0; --i) {
		if (((1LL << i)&b) && ((1LL << i) & a)) {
			LL t2 = b;
			LL t1 = a;
			for (int j = i - 1; j >= 0; --j)
				A[j] = (1LL << j)&t1, B[j] = (1LL << j)&t2;
			memset(F, -1, sizeof(F));
			ans += solve(i - 1, 1, 1, 1, 1);
			ans %= mod;
			break;
		}
		else if ((1LL << i)&b) {
			LL t2 = b;
			LL t1 = (1LL << i);
			for (int j = i - 1; j >= 0; --j)
				A[j] = (1LL << j)&t1, B[j] = (1LL << j)&t2;
			memset(F, -1, sizeof(F));
			ans += solve(i - 1, 1, 1, 1, 1);
			ans %= mod;
			b = t1-1;
		}
	}

	cout << ans << endl;

	return 0;
}

/*

00
*/



Compiler output:
a.cc:3:1: error: 'LL' does not name a type
    3 | LL F[maxn][2][2][2][2];
      | ^~
a.cc:6:1: error: 'LL' does not name a type
    6 | LL solve(int n, int a1, int b1, int a2, int b2) {
      | ^~
a.cc: In function 'int main()':
a.cc:34:9: error: 'LL' was not declared in this scope
   34 |         LL a, b; cin >> a >> b;
      |         ^~
a.cc:34:18: error: 'cin' was not declared in this scope
   34 |         LL a, b; cin >> a >> b;
      |                  ^~~
a.cc:34:25: error: 'a' was not declared in this scope
   34 |         LL a, b; cin >> a >> b;
      |                         ^
a.cc:34:30: error: 'b' was not declared in this scope
   34 |         LL a, b; cin >> a >> b;
      |                              ^
a.cc:35:11: error: expected ';' before 'ans'
   35 |         LL ans = 0;
      |           ^~~~
      |           ;
a.cc:38:27: error: expected ';' before 't2'
   38 |                         LL t2 = b;
      |                           ^~~
      |                           ;
a.cc:39:27: error: expected ';' before 't1'
   39 |                         LL t1 = a;
      |                           ^~~
      |                           ;
a.cc:41:51: error: 't1' was not declared in this scope
   41 |                                 A[j] = (1LL << j)&t1, B[j] = (1LL << j)&t2;
      |                                                   ^~
a.cc:41:73: error: 't2' was not declared in this scope
   41 |                                 A[j] = (1LL << j)&t1, B[j] = (1LL << j)&t2;
      |                                                                         ^~
a.cc:42:32: error: 'F' was not declared in this scope
   42 |                         memset(F, -1, sizeof(F));
      |                                ^
a.cc:42:25: error: 'memset' was not declared in this scope
   42 |                         memset(F, -1, sizeof(F));
      |                         ^~~~~~
a.cc:1:1: note: 'memset' is defined in header '<cstring>'; this is probably fixable by adding '#include <cstring>'
  +++ |+#include <cstring>
    1 | //
a.cc:43:25: error: 'ans' was not declared in this scope
   43 |                         ans += solve(i - 1, 1, 1, 1, 1);
      |                         ^~~
a.cc:43:32: error: 'solve' was not declared in this scope
   43 |                         ans += solve(i - 1, 1, 1, 1, 1);
      |                                ^~~~~
a.cc:44:32: error: 'mod' was not declared in this scope
   44 |                         ans %= mod;
      |                                ^~~
a.cc:48:27: error: expected ';' before 't2'
   48 |                         LL t2 = b;
      |                           ^~~
      |                           ;
a.cc:49:27: error: expected ';' before 't1'
   49 |                         LL t1 = (1LL << i);
      |                           ^~~
      |                           ;
a.cc:51:51: error: 't1' was not declared in this scope
   51 |                                 A[j] = (1LL << j)&t1, B[j] = (1LL << j)&t2;
      |                                                   ^~
a.cc:51:73: error: 't2' was not declared in this scope
   51 |                                 A[j] = (1LL << j)&t1, B[j] = (1LL << j)&t2;
      |                                                                         ^~
a.cc:52:32: error: 'F' was not declared in this scope
   52 |                         memset(F, -1, sizeof(F));
      |                                ^
a.cc:52:25: error: 'memset' was not declared in this scope
   52 |                         memset(F, -1, sizeof(F));
      |                         ^~~~~~
a.cc:52:25: note: 'memset' is defined in header '<cstring>'; this is probably fixable by adding '#include <cstring>'
a.cc:53:25: error: 'ans' was not declared in this scope
   53 |                         ans += solve(i - 1, 1, 1, 1, 1);
      |                         ^~~
a.cc:53:32: error: 'solve' was not declared in this scope
   53 |                         ans += solve(i - 1, 1, 1, 1, 1);
      |                                ^~~~~
a.cc:54:32: error: 'mod' was not declared in this scope
   54 |                         ans %= mod;
      |                                ^~~
a.cc:55:29: error: 't1' was not declared in this scope
   55 |                         b = t1-1;
      |                             ^~
a.cc:59:9: error: 'cout' was not declared in this scope
   59 |         cout << ans << endl;
      |         ^~~~
a.cc:59:17: error: 'ans' was not declared in this scope
   59 |         cout << ans << endl;
      |                 ^~~
a.cc:59:24: error: 'endl' was not declared in this scope
   59 |         cout << ans << endl;
      |                        ^~~~