预处理加有一点儿前缀和的知识，问题在于知不知道欧拉筛和埃筛，挺细节的，千万记得别i等N 会j

#include <iostream>
using namespace std;
const int N = 1e7 + 9;
int a[N], p[N], q[N];
inline void sieve(int n) {
    for (int i = 0; i <= n; i++) p[i] = 1;
    p[0] = p[1] = 0;
    for (int i = 2; i * i <= n; i++)
        if (p[i])
            for (int j = i * i; j <= n; j += i)
                p[j] = 0;
}
inline int d(int x) {
    int s = 0;
    while (x) {
        s += x % 10;
        x /= 10;
    }
    return s;
}
int main() {
    ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);
    sieve(N - 1);
    for (int i = 2; i < N; i++)
        q[i] = p[d(i)];
    for (int i = 1; i < N; i++) {
        a[i] = a[i - 1];
        if (p[i] && q[i]) a[i]++;
    }
    int t, l, r;
    cin >> t;
    while (t--) {
        cin >> l >> r;
        cout << a[r] - a[l - 1] << endl;
    }    
    return 0;
}    

数位dp