delete pics to save space

history_source/ccf 入门篇/U4/4.2.4.cpp

@@ -0,0 +1,20 @@
+#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;
+	}
+}