#include "bits/stdc++.h"

using namespace std;
#ifdef _DEBUG
#define _GLIBCXX_DEBUG
#include "dump.hpp"
#else
#define dump(...)
#endif

#define int long long
#define ll long long
#define ll1 1ll
#define ONE 1ll
#define DBG 1
#define rep(i, a, b) for (int i = (a); i < (b); i++)
#define rrep(i, a, b) for (int i = (b)-1; i >= (a); i--)
#define loop(n) rep(loop, (0), (n))
#define all(c) begin(c), end(c)
const int INF =
sizeof(int) == sizeof(long long) ? 0x3f3f3f3f3f3f3f3fLL : 0x3f3f3f3f;
const int MOD = (int)(1e9) + 7;
const double PI = acos(-1);
const double EPS = 1e-9;
#define fi first
#define se second
#define pb push_back
#define eb emplace_back
using pii = pair<int, int>;
// template<class T> ostream &operator<<(ostream &os,T &t){dump(t);return os;}
template <typename T, typename S>
istream &operator>>(istream &is, pair<T, S> &p) {
	is >> p.first >> p.second;
	return is;
}
template <typename T, typename S>
ostream &operator<<(ostream &os, pair<T, S> &p) {
	os << p.first << " " << p.second;
	return os;
}

template <typename T> void printvv(const vector<vector<T>> &v) {
	cerr << endl;
	rep(i, 0, v.size()) rep(j, 0, v[i].size()) {
		if (typeid(v[i][j]).name() == typeid(INF).name() and v[i][j] == INF) {
			cerr << "INF";
		}
		else
			cerr << v[i][j];
		cerr << (j == v[i].size() - 1 ? '\n' : ' ');
	}
	cerr << endl;
}
/*
typedef __int128_t Int;
std::ostream &operator<<(std::ostream &dest, __int128_t value) {
std::ostream::sentry s(dest);
  if (s) {
	__uint128_t tmp = value < 0 ? -value : value;
	char buffer[128];
	char *d = std::end(buffer);
	do {
	  --d;
	  *d = "0123456789"[tmp % 10];
	  tmp /= 10;
	} while (tmp != 0);
	if (value < 0) {
	  --d;
	  *d = '-';
	}
	int len = std::end(buffer) - d;
	if (dest.rdbuf()->sputn(d, len) != len) {
	  dest.setstate(std::ios_base::badbit);
	}
  }
  return dest;
}

__int128 parse(string &s) {
  __int128 ret = 0;
  for (int i = 0; i < s.length(); i++)
	if ('0' <= s[i] && s[i] <= '9')
	  ret = 10 * ret + s[i] - '0';
  return ret;
}
*/

#ifndef _DEBUG
#define printvv(...)
#endif
void YES(bool f) { cout << (f ? "YES" : "NO") << endl; }
void Yes(bool f) { cout << (f ? "Yes" : "No") << endl; }
template <class T> bool chmax(T &a, const T &b) {
	if (a < b) {
		a = b;
		return true;
	}
	return false;
}
template <class T> bool chmin(T &a, const T &b) {
	if (a > b) {
		a = b;
		return true;
	}
	return false;
}
struct UnionFind {
	vector<int> parent;
	int size;
	UnionFind(int n) :parent(n, -1), size(n) {}
	bool unite(int x, int y) {
		x = root(x); y = root(y);
		if (x == y)return false;
		if (size_of(x) < size_of(y))swap(x, y);
		parent[x] += parent[y]; parent[y] = x; size--;
		return true;
	}
	bool same(int x, int y) { return root(x) == root(y); }
	int root(int x) { return parent[x] < 0 ? x : parent[x] = root(parent[x]); }
	int size_of(int x) { return -parent[root(x)]; }
};

signed main(signed argc, char *argv[]) {
	cin.tie(0);
	ios::sync_with_stdio(false);
	cout << fixed << setprecision(12);

	int N, M; cin >> N >> M;
	string s; cin >> s;
	vector<int>a(M), b(M); rep(i, 0, M) { cin >> a[i] >> b[i]; a[i]--, b[i]--; }
	vector<vector<int>>g(N);
	rep(i, 0, M) {
		if (a[i] != b[i]) {
			g[a[i]].eb(b[i]);
			g[b[i]].eb(a[i]);
		}
	}
	rep(i, 0, M) {
		if (a[i] == b[i]) {
			g.eb(vector<int>());
			for (auto v : g[a[i]]) {
				g[N].eb(v);
				g[v].eb(N);
			}
			s.pb(s[a[i]]);
			g[a[i]].eb(N);
			g[N].eb(a[i]);
			N++;
		}
	}
	vector<vector<int>>visited(N, vector<int>(4));
	vector<int>next(N, -1);
	function<int(int, int)> dfs = [&](int v, int c) {
		dump(v, c);
		visited[v][c] = 1;
		bool ret = false;
		for (auto u : g[v]) {
			if (c == 0 and s[u] == 'A' or c == 1 and s[u] == 'B' or c == 2 and s[u] == 'B' or c == 3 and s[u] == 'A') {
				if (visited[u][(c + 1) % 4] == 0) {
					bool res = dfs(u, (c + 1) % 4);
					if (res) {
						next[v] = u;
						return true;
					}
				}
				else if (visited[u][(c + 1) % 4] == 1) {
					next[v] = u;
					return true;
				}
			}
		}
		visited[v][c] = 2;
		return false;
	};
	bool ans = false;
	rep(i, 0, N) {
		if (s[i] == 'A' and visited[i][0]==0) {
			ans = dfs(i, 0);
			
		}
		else if (s[i] == 'B' and visited[i][2] == 0) {
			ans = dfs(i, 2);
		}
		if (ans)break;
	}
	rep(i, 0, N) {
		dump(i, s[i], g[i]);
	}
	dump(next);
	Yes(ans);

	return 0;
}


Measured memory_bytes: 39504