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digitprime.cpp
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digitprime.cpp
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#include <iostream>
#include <vector>
#include <algorithm>
#include <cmath>
#include <iomanip>
#include <cstring>
#include <map>
#include <sstream>
using namespace std;
#define F first
#define S second
typedef long long ll;
typedef pair<int,int> pii;
int p[1000000];
bool c[1000000];
int s(int n){
int ret = 0;
while(n){
ret+=(n%10);
n/=10;
}
return ret;
}
int main(){
ios::sync_with_stdio(false);
cin.tie(0);
// freopen("in.txt","r",stdin);
// freopen("out.txt","w",stdout);
memset(c,true,sizeof(c));
memset(p,0,sizeof(p));
c[0] = false;
c[1] = false;
for(int i=2;i<1000000;i++){
p[i] = p[i-1];
if(c[i]){
if(c[s(i)])
p[i]++;
for(int j=2*i;j<1000000;j+=i)
c[j] = false;
}
}
int t;
cin>>t;
while(t--){
int l,r;
cin>>l>>r;
if(l>=1)
cout<<p[r]-p[l-1]<<'\n';
else
cout<<p[r]<<'\n';
}
return 0;
}