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***************************************************************************************************
 5
****.

no yes no no no yes yes no yes yes yes yes yes yes no yes yes yes yes yes yes yes yes yes yes yes no no no yes yes yes yes no no yes yes yes yes yes no yes yes no no no yes yes no yes yes no no no yes yes yes yes no yes yes yes no
import static java.lang.Math.*;
import java.util.*;
import java.io.*;

public class A {

	public void solve() throws Exception {
		
		int n = nextInt();
		char[] map = nextLine().toCharArray();
		
		for (int i=1; i<=25; ++i) {
			for (int j=0; j<n; ++j) {
				boolean ok = true;
				for (int k=0; k<5; ++k) {
					if (j+k*i >= n || map[j+k*i]=='.') {
						ok = false;
					}
				}
				if (ok) {
					println("yes");
					return;
				}
			}
		}
		
		println("no");
		
	}

	

	////////////////////////////////////////////////////////////////////////////
	
	boolean showDebug = true;
	static boolean useFiles = false;
	static String inFile = "input.txt";
	static String outFile = "output.txt";

	double EPS = 1e-7;
	int INF = Integer.MAX_VALUE;
	long INFL = Long.MAX_VALUE;
	double INFD = Double.MAX_VALUE;

	
	int absPos(int num) {
		return num<0 ? 0:num;
	}
	long absPos(long num) {
		return num<0 ? 0:num;
	}
	double absPos(double num) {
		return num<0 ? 0:num;
	}
	
	int min(int... nums) {
		int r = nums[0];
		for (int i=1; i<nums.length; ++i)
			if (nums[i]<r) r=nums[i];
		return r;
	}
	int max(int... nums) {
		int r = nums[0];
		for (int i=1; i<nums.length; ++i)
			if (nums[i]>r) r=nums[i];
		return r;
	}
	long minL(long... nums) {
		long r = nums[0];
		for (int i=1; i<nums.length; ++i)
			if (nums[i]<r) r=nums[i];
		return r;
	}
	long maxL(long... nums) {
		long r = nums[0];
		for (int i=1; i<nums.length; ++i)
			if (nums[i]>r) r=nums[i];
		return r;
	}
	double minD(double... nums) {
		double r = nums[0];
		for (int i=1; i<nums.length; ++i)
			if (nums[i]<r) r=nums[i];
		return r;
	}
	double maxD(double... nums) {
		double r = nums[0];
		for (int i=1; i<nums.length; ++i)
			if (nums[i]>r) r=nums[i];
		return r;
	}
	
	long sumArr(int[] arr) {
		long res = 0;
		for (int i=0; i<arr.length; ++i)
			res+=arr[i];
		return res;
	}
	long sumArr(long[] arr) {
		long res = 0;
		for (int i=0; i<arr.length; ++i)
			res+=arr[i];
		return res;
	}
	double sumArr(double[] arr) {
		double res = 0;
		for (int i=0; i<arr.length; ++i)
			res+=arr[i];
		return res;
	}

	long partsFitCnt(long partSize, long wholeSize) {
		return (partSize+wholeSize-1)/partSize;
	}

	boolean odd(long num) {
		return (num&1)==1;
	}
	
	boolean hasBit(int num, int pos) {
		return (num&(1<<pos))>0;
	}

	boolean isLetter(char c) {
		return (c>='a' && c<='z') || (c>='A' && c<='Z');
	}
	boolean isLowercase(char c) {
		return (c>='a' && c<='z');
	}
	boolean isUppercase(char c) {
		return (c>='A' && c<='Z');
	}
	boolean isDigit(char c) {
		return (c>='0' && c<='9');
	}
	
	boolean charIn(String chars, String s) {
		if (s==null) return false;
		if (chars==null || chars.equals("")) return true;
		for (int i=0; i<s.length(); ++i)
			for (int j=0; j<chars.length(); ++j)
				if (chars.charAt(j)==s.charAt(i)) return true;
		return false;
	}
	
	String stringn(String s, int n) {
		if (n<1 || s==null) return "";
		StringBuilder sb = new StringBuilder(s.length()*n);
		for (int i=0; i<n; ++i) sb.append(s);
		return sb.toString();
	}
	String str(Object o) {
		if (o==null) return "";
		return o.toString();
	}


	long timer = System.currentTimeMillis();
	void startTimer() {
		timer = System.currentTimeMillis();
	}
	void stopTimer() {
		System.err.println("time: "+(System.currentTimeMillis()-timer)/1000.0);
	}


	static class InputReader {
		private byte[] buf;
		private int bufPos = 0, bufLim = -1;
		private InputStream stream;
		public InputReader(InputStream stream, int size) {
			buf = new byte[size];
			this.stream = stream;
		}
		private void fillBuf() throws IOException {
			bufLim = stream.read(buf);
			bufPos = 0;
		}
		char read() throws IOException {
			if (bufPos>=bufLim) fillBuf(); 
			return (char)buf[bufPos++];
		}
		boolean hasInput() throws IOException {
			if (bufPos>=bufLim) fillBuf();
			return bufPos<bufLim;
		}
	}
	
	static InputReader inputReader;
	static BufferedWriter outputWriter;

	char nextChar() throws IOException {
		return inputReader.read();
	}
	char nextNonWhitespaceChar() throws IOException {
		char c = inputReader.read();
		while (c<=' ') c=inputReader.read();
		return c;
	}
	String nextWord() throws IOException {
		StringBuilder sb = new StringBuilder();
		char c = inputReader.read();
		while (c<=' ') c=inputReader.read();
		while (c>' ') {
			sb.append(c);
			c = inputReader.read();
		}
		return new String(sb);
	}
	String nextLine() throws IOException {
		StringBuilder sb = new StringBuilder();
		char c = inputReader.read();
		while (c<=' ') c=inputReader.read();
		while (c!='\n' && c!='\r') {
			sb.append(c);
			c = inputReader.read();
		}
		return new String(sb);
	}
	int nextInt() throws IOException {
		int r = 0;
		char c = nextNonWhitespaceChar();
		boolean neg = false;
		if (c=='-') neg=true;
		else r=c-48;
		c = nextChar();
		while (c>='0' && c<='9') {
			r*=10;
			r+=c-48;
			c=nextChar();
		}
		return neg ? -r:r;
	}
	long nextLong() throws IOException {
		long r = 0;
		char c = nextNonWhitespaceChar();
		boolean neg = false;
		if (c=='-') neg=true;
		else r = c-48;
		c = nextChar();
		while (c>='0' && c<='9') {
			r*=10L;
			r+=c-48L;
			c=nextChar();
		}
		return neg ? -r:r;
	}
	double nextDouble() throws NumberFormatException, IOException {
		return Double.parseDouble(nextWord());
	}
	int[] nextArr(int size) throws NumberFormatException, IOException {
		int[] arr = new int[size];
		for (int i=0; i<size; ++i)
			arr[i] = nextInt();
		return arr;
	}
	long[] nextArrL(int size) throws NumberFormatException, IOException {
		long[] arr = new long[size];
		for (int i=0; i<size; ++i)
			arr[i] = nextLong();
		return arr;
	}
	double[] nextArrD(int size) throws NumberFormatException, IOException {
		double[] arr = new double[size];
		for (int i=0; i<size; ++i)
			arr[i] = nextDouble();
		return arr;
	}
	String[] nextArrS(int size) throws NumberFormatException, IOException {
		String[] arr = new String[size];
		for (int i=0; i<size; ++i)
			arr[i] = nextWord();
		return arr;
	}
	char[] nextArrCh(int size) throws IOException {
		char[] arr = new char[size];
		for (int i=0; i<size; ++i)
			arr[i] = nextNonWhitespaceChar();
		return arr;
	}
	char[][] nextArrCh(int rows, int columns) throws IOException {
		char[][] arr = new char[rows][columns];
		for (int i=0; i<rows; ++i)
			for (int j=0; j<columns; ++j)
				arr[i][j] = nextNonWhitespaceChar();
		return arr;
	}
	char[][] nextArrChBorders(int rows, int columns, char border) throws IOException {
		char[][] arr = new char[rows+2][columns+2];
		for (int i=1; i<=rows; ++i)
			for (int j=1; j<=columns; ++j)
				arr[i][j] = nextNonWhitespaceChar();
		for (int i=0; i<columns+2; ++i) {
			arr[0][i] = border;
			arr[rows+1][i] = border;
		}
		for (int i=0; i<rows+2; ++i) {
			arr[i][0] = border;
			arr[i][columns+1] = border;
		}
		return arr;
	}

	void printf(String format, Object... args) throws IOException {
		outputWriter.write(String.format(format, args));
	}
	void print(Object o) throws IOException {
		outputWriter.write(o.toString());
	}
	void println(Object o) throws IOException {
		outputWriter.write(o.toString());
		outputWriter.newLine();
	}
	void print(Object... o) throws IOException {
		for (int i=0; i<o.length; ++i) {
			if (i!=0) outputWriter.write(' ');
			outputWriter.write(o[i].toString());
		}
	}
	void println(Object... o) throws IOException {
		print(o);
		outputWriter.newLine();
	}
	void printn(Object o, int n) throws IOException {
		String s = o.toString();
		for (int i=0; i<n; ++i) {
			outputWriter.write(s);
			if (i!=n-1) outputWriter.write(' ');
		}
	}
	void printnln(Object o, int n) throws IOException {
		printn(o, n);
		outputWriter.newLine();
	}
	void printArr(int[] arr) throws IOException {
		for (int i=0; i<arr.length; ++i) {
			if (i!=0) outputWriter.write(' ');
			outputWriter.write(Integer.toString(arr[i]));
		}
	}
	void printArr(long[] arr) throws IOException {
		for (int i=0; i<arr.length; ++i) {
			if (i!=0) outputWriter.write(' ');
			outputWriter.write(Long.toString(arr[i]));
		}
	}
	void printArr(double[] arr) throws IOException {
		for (int i=0; i<arr.length; ++i) {
			if (i!=0) outputWriter.write(' ');
			outputWriter.write(Double.toString(arr[i]));
		}
	}
	void printArr(String[] arr) throws IOException {
		for (int i=0; i<arr.length; ++i) {
			if (i!=0) outputWriter.write(' ');
			outputWriter.write(arr[i]);
		}
	}
	void printlnArr(int[] arr) throws IOException {
		printArr(arr);
		outputWriter.newLine();
	}
	void printlnArr(long[] arr) throws IOException {
		printArr(arr);
		outputWriter.newLine();
	}
	void printlnArr(double[] arr) throws IOException {
		printArr(arr);
		outputWriter.newLine();
	}
	void printlnArr(String[] arr) throws IOException {
		printArr(arr);
		outputWriter.newLine();
	}
	void halt(Object... o) throws IOException {
		if (o.length!=0) println(o);
		outputWriter.flush(); outputWriter.close();
		System.exit(0);
	}
	
	void debug(Object... o) {
		if (showDebug) System.err.println(Arrays.deepToString(o));
	}


	public static void main(String[] args) throws Exception {
		Locale.setDefault(Locale.US);
		if (!useFiles) {
			inputReader = new InputReader(System.in, 1<<16);
			outputWriter = new BufferedWriter(new OutputStreamWriter(System.out), 1<<16);
		} else {
			inputReader = new InputReader(new FileInputStream(new File(inFile)), 1<<16);
			outputWriter = new BufferedWriter(new OutputStreamWriter(new FileOutputStream(new File(outFile))), 1<<16);
		}
		new A().solve();
		outputWriter.flush(); outputWriter.close();
	}
}
