import java.io.IOException;
import java.io.InputStream;
import java.util.Scanner;
public class Main {
    static final char[] chars="CPCT".toCharArray();
    static final char[] CPC="CPC".toCharArray();
    static int last=0;
    public static void main(String[] args) {
        FastScanner scanner=new FastScanner();
        int len=scanner.readInt();
        scanner.read=0;
        int o=0;
        scanner.max=len;
        while (scanner.hasNextByte()){
            skipTillCPCT(o,scanner);
            if(ableToBeF(scanner)) o++;
        }
        System.out.println(o);
    }
    private static boolean ableToBeF(FastScanner scanner){
        last=0;
        int c=scanner.readByte();
        if(c=='F') return true;
        for(int i=0;i<3;i++){
            if(c!=CPC[i]){
                last=c;
                return false;
            }
            if(i!=2) c=scanner.readByte();
        }
        last=0;
        return true;
    }
    private static void skipTillCPCT(int last,FastScanner scanner){
        int c;
        int index=0;
        if(last=='C') index++;
        while ((c=scanner.readByte())!=-1&&index!=3){
            if(c!=chars[index]){
                index=0;
                continue;
            }
            index++;
        }
    }

    private static class FastScanner {
        private final InputStream in = System.in;
        private final byte[] buffer = new byte[1024];
        private int ptr = 0;
        private int buflen = 0;
        public int read=0;
        public int max=20;
        private boolean hasNextByte() {
            if(max<=read) return false;
            if (ptr < buflen) {
                return true;
            }else{
                ptr = 0;
                try {
                    buflen = in.read(buffer);
                } catch (IOException e) {
                    e.printStackTrace();
                }
                return buflen > 0;
            }
        }
        private int readByte() {
            if (hasNextByte()){
            read++;
            return buffer[ptr++];
        } else return -1;}
        private static boolean isPrintableChar(int c) { return 33 <= c && c <= 126;}

        public int readInt(){
            int b = readByte();
            int n=0;
            while(true){
                if ('0' <= b && b <= '9') {
                    n *= 10;
                    n += b - '0';
                }else if(b == -1 || !isPrintableChar(b)){
                    return n;
                }else{
                    throw new NumberFormatException();
                }
                b = readByte();
            }
        }
    }
}