C++ :

#include <bits/stdc++.h>
using namespace std;

int main(){
	string s,w;
	int c = 0;
	getline(cin,s);
	
	for(int i = 0;i < s.size();i++){
		if(s[i] != ' '){
			w = w + s[i];
			if(i==s.size()-1 || s[i+1]==' '){
				
				if(w == "bug") c++;
				
				w = "";
			}
		}
	}
	
	cout<<c;
	return 0;
}

Java :

import java.util.Scanner;

public class Main{
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        String n = sc.nextLine();
        char c;
        int c1 = 0;
        String s2;
        String s1 = n.toUpperCase();
        ;
        String[] s = s1.split(" ");
        String x = "BUG";
        for (int i = 0; i < s.length; i++) {
            c = s1.charAt(i);
            s2 = s + "";
            if (x.equals(s[i])) {
                c1++;
            }
            //    System.out.print(s[i]+" ");
        }
        System.out.print(c1);
    }
}