Files
OI-source/history_source/ccf 入门篇/U4/4.2.4.cpp
2023-08-03 09:22:52 +08:00

21 lines
299 B
C++

#include<iostream>
#include<string>
#include<sstream>
using namespace std;
int main()
{
string j;
stringstream num;
int s,b,n;
while(true)
{
cin>>s>>b;
n=0;
num.flush();
for(int i=0;i<b-s+1;i++) num<<s+i;
num>>j;
for(int i=0;i<j.size();i++) if(j[i]=='2') n++;
cout<<n<<endl;
}
}