写出一个程序，接受一个由字母、数字和空格组成的字符串，和一个字母，然后输出输入字符串中该字母的出现次数。不区分大小写。

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main {
public static void main(String[] args) throws IOException {
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
char[] chars1 = br.readLine().toLowerCase().toCharArray();
char[] chars2 = br.readLine().toLowerCase().toCharArray();
int count = 0;
for (int i = 0;i<chars1.length;i++){
if((chars1[i]>=65||chars1[i]<90)&&(chars1[i]==chars2[0])){
count++;
}
}
System.out.println(count);
}
}