#include <string>
#include <vector>
#include <algorithm>
#include <numeric>
#include <set>
#include <map>
#include <queue>
#include <iostream>
#include <sstream>
#include <cstdio>
#include <cmath>
#include <ctime>
#include <cstring>
#include <cctype>
#include <cassert>
#include <limits>
#include <functional>
#define rep(i,n) for(int (i)=0;(i)<(int)(n);++(i))
#define rer(i,l,u) for(int (i)=(int)(l);(i)<=(int)(u);++(i))
#define reu(i,l,u) for(int (i)=(int)(l);(i)<(int)(u);++(i))
#if defined(_MSC_VER) || __cplusplus > 199711L
#define aut(r,v) auto r = (v)
#else
#define aut(r,v) __typeof(v) r = (v)
#endif
#define each(it,o) for(aut(it, (o).begin()); it != (o).end(); ++ it)
#define all(o) (o).begin(), (o).end()
#define pb(x) push_back(x)
#define mp(x,y) make_pair((x),(y))
#define mset(m,v) memset(m,v,sizeof(m))
#define INF 0x3f3f3f3f
#define INFL 0x3f3f3f3f3f3f3f3fLL
using namespace std;
typedef vector<int> vi; typedef pair<int,int> pii; typedef vector<pair<int,int> > vpii; typedef long long ll;
template<typename T, typename U> inline void amin(T &x, U y) { if(y < x) x = y; }
template<typename T, typename U> inline void amax(T &x, U y) { if(x < y) x = y; }


int readNatural(int lo, int up) {
	assert(0 <= lo && lo <= up);
	int x = 0;
	while(1) {
		int d = getchar();
		if(!('0' <= d && d <= '9')) {
			ungetc(d, stdin);
			break;
		}
		d -= '0';
		assert(d <= up && x <= (up - d) / 10);
		x = x * 10 + d;
	}
	assert(lo <= x && x <= up);
	return x;
}

void readSpace() { int c = getchar(); assert(c == ' '); }
static bool read_eof = false;
void readEOL() {
	int c = getchar();
	if(c == EOF) {
		assert(!read_eof);
		read_eof = true;
	}else {
		assert(c == '\n');
	}
}

int readString(char *buf, int minLen, int maxLen, bool charactors[128]) {
	assert(0 <= minLen && minLen <= maxLen);
	int len = 0;
	while(1) {
		int c = getchar();
		if(!(0 <= c && c < 128) || !charactors[c]) {
			ungetc(c, stdin);
			break;
		}
		assert(len < maxLen);
		buf[len ++] = c;
	}
	assert(minLen <= len && len <= maxLen);
	buf[len] = 0;
	return len;
}


int main() {
	bool zeroone[128] = {};
	zeroone['0'] = zeroone['1'] = true;
	int N = readNatural(1, (int)1e6); readEOL();
	char *S = new char[N+1];
	readString(S, N, N, zeroone); readEOL();
	assert(!read_eof);
	bool ans;
	if(N >= 4) {
		ans = true;
	}else {
		ans = false;
		rer(len, 1, N/2) rer(i, 0, N-len*2)
			ans |= memcmp(S + i, S + i + len, len) == 0;
	}
	puts(ans ? "YES" : "NO");
	return 0;
}