import java.util.Scanner;

public class Main {
 
    public static void main( String[] args ) {
 
        Scanner sc = new Scanner( System.in );
      
        int n = sc.nextInt();  
        String s = sc.next(); 
      
        String replaceStr = s.replaceAll( "ABC", "" );
        System.out.println( ( n - replaceStr.length() ) / 3 );
    }
}
/tmp/hf-datasets-cache/medium/datasets/42704881117311-config-parquet-and-info-qiankunmu-Project_CodeNet-896c9d36/hub/datasets--qiankunmu--Project_CodeNet_Python800_and_Java250/snapshots/c899fde44a77ba1cc14973ed3de064e4ff3aadc7/Project_CodeNet_Java250.tar.gz