pow函数实现

#include <iostream>
#include <cmath>
using namespace std;

int main() {
    int l, r;
    cin >> l >> r;
    
    int ans = 0;
    for (int n = l; n <= r; n++) {
        bool flag = false;
        for (int x = 0; x <= 13; x++) {
            int px = (int)pow(2, x);
            for (int y = x; y <= 13; y++) {
                int py = (int)pow(2, y);
                if (px + py == n) {
                    flag = true;
                    break; // 可选：提前退出内层循环
                }
            }
            if (flag) break; // 可选：提前退出 x 循环
        }
        if (flag) ans++;
    }
    cout << ans << endl;
    return 0;
}