#include <iostream>
#include <string>
#include <cmath>
#include<algorithm>
#include<stack>
#include<queue>
#include<map>
#include<set>
#include<iomanip>
#define _USE_MATH_DEFINES
#include <math.h>
#include <functional>
#include<complex>
using namespace std;

#define rep(i,x) for(ll i=0;i<x;i++)
#define repn(i,x) for(ll i=1;i<=x;i++)

typedef long long ll;
const ll INF = 1e17;
const ll MOD = 1000000007;
const ll MAX = 4000001;
const long double eps = 1E-14;

ll max(ll a, ll b) {
	if (a > b) { return a; }
	return b;
}

ll min(ll a, ll b) {
	if (a > b) { return b; }
	return a;
}

ll gcd(ll a, ll b) {
	if (b == 0) { return a; }
	if (a < b) { return gcd(b, a); }
	return gcd(b, a % b);
}

ll lcm(ll a, ll b) {
	return a / gcd(a, b) * b;
}

struct edge {
	ll ind;
	ll fr;
	ll to;
	ll d;
};

class mint {
	long long x;
public:
	mint(long long x = 0) : x((x% MOD + MOD) % MOD) {}
	mint operator-() const {
		return mint(-x);
	}
	mint& operator+=(const mint& a) {
		if ((x += a.x) >= MOD) x -= MOD;
		return *this;
	}
	mint& operator-=(const mint& a) {
		if ((x += MOD - a.x) >= MOD) x -= MOD;
		return *this;
	}
	mint& operator*=(const  mint& a) {
		(x *= a.x) %= MOD;
		return *this;
	}
	mint operator+(const mint& a) const {
		mint res(*this);
		return res += a;
	}
	mint operator-(const mint& a) const {
		mint res(*this);
		return res -= a;
	}
	mint operator*(const mint& a) const {
		mint res(*this);
		return res *= a;
	}

	mint pow(ll t) const {
		if (!t) return 1;
		mint a = pow(t >> 1);
		a *= a;
		if (t & 1) a *= *this;
		return a;
	}

	// for prime MOD
	mint inv() const {
		return pow(MOD - 2);
	}
	mint& operator/=(const mint& a) {
		return (*this) *= a.inv();
	}
	mint operator/(const mint& a) const {
		mint res(*this);
		return res /= a;
	}

	friend ostream& operator<<(ostream& os, const mint& m) {
		os << m.x;
		return os;
	}
};

mint pw(mint a, ll b) {
	if (b == 0) { return 1; }
	mint ret = pw(a, b >> 1);
	ret *= ret;
	if (b & 1) { ret *= a; }
	return ret;
}

typedef vector<ll> vll;
typedef vector<vector<ll>> vvll;
typedef vector<vector<vector<ll>>> vvvll;

typedef vector<mint> vmint;
typedef vector<vector<mint>> vvmint;
typedef vector<vector<vector<mint>>> vvvmint;

//////////////////////////////////////

int main() {
	ll N, M;
	cin >> N >> M;
	string t;
	cin >> t;
	vll s(N + 1);
	repn(i, N) {
		if (t[i - 1] == 'A') { s[i] = 0; }
		else { s[i] = 1; }
	}
	//repn(i,N)cout <<s[i]<<endl;
	vvll g(N + 1);
	repn(i, M) {
		ll a, b;
		cin >> a >> b;
		g[a].push_back(b);
		g[b].push_back(a);
	}
	//cout << N << endl;
	vvll out(N+1, vll(2,0));
	repn(v, N) {
		for (ll w : g[v]) {
			out[w][s[v]]++;
		}
	}

	vector<ll> use(N + 1,1);
	queue<ll> q;
	repn(v, N) {
		if (out[v][0] == 0 || out[v][1] == 0) { use[v] = 0; q.push(v); }
	}

	while (!q.empty()) {
		ll v = q.front();
		//cout << v << endl;
		q.pop();
		for (ll w : g[v]) {
			if (use[w] == 0) { continue; }
			
			out[w][s[v]]--;
			if (out[w][s[v]] == 0) {
				use[w] = 0;
				q.push(w);
			}
		}
	}

	bool isa = 0;
	bool isb = 0;
	repn(v, N) {
		if (use[v] == 1 && s[v] == 0) { isa = 1; }
		if (use[v] == 1 && s[v] == 1) { isb = 1; }
	}

	if (isa && isb) { cout << "Yes" << endl; }
	else { cout << "No" << endl; }
}


Measured memory_bytes: 28656