题解

#include<iostream>
using namespace std;
int main(){
    int l,r,sum=0;
    cin>>l>>r;
    for(int i=l;i<=r;i++){
        int x=i;
        while(x!=0){
            if(x%10==2){
                sum++;
            }
            x/=10;
        }
    }
    cout<<sum;
    return 0;
}