运行超时求救!!!全是Time Limit Exceeded!

我猜是for循环套while循环时间复杂度太高-_-|

#include<bits/stdc++.h>
using namespace std;
int main(){
	int l,r,s=0;
	cin>>l>>r;
	for(int i=l;i<=r;i++){
	    int flag=0,d=i;
            while(d>0){
                if(d%10==2)flag++;
            }s=s+flag;
	}cout<<s;
    return 0;
}