#include <bits/stdc++.h>
#include <iomanip>
 
using namespace std;
 
typedef long long LL;
typedef long double LD;
typedef pair<int, int> PII;
typedef pair<LL, LL> PLL;
typedef pair<LD, LD> PLDLD;
typedef vector<int> VI;
typedef vector<LL> VLL;
typedef vector<char> VB;
 
#define FOR(i,a,b) for(int i=(a);i<(int)(b);++i)
#define REP(i,n) FOR(i,0,n)
#define CLR(a) memset((a), 0 ,sizeof(a))
#define ALL(a) a.begin(),a.end()
#define endl "\n"
 
const LD EPS=1e-10;
const long long INFLL=(LL)(1e9)*(LL)(1e9);
const int INF=1e9+7;

template<class T>
void chmin(T& a, const T b)
{
	if(a>b)
		a=b;
}
template<class T>
void chmax(T& a, const T b)
{
	if(a<b)
		a=b;
}
 
const LL powLL(const LL p, const LL q)
{
	LL t=1;
	for(int i=0;i<q;i++)
		t*=p;
	return t;
}

template <typename T>
struct has_iter
{
	private:
		template <typename U>
		static constexpr true_type check(typename U::iterator*);
		template <typename U>
		static constexpr false_type check(...);

	public:
		static constexpr bool value = decltype(check<T>(nullptr))::value;
};


template<typename T, typename U = typename T::iterator>
void print(const T& container)
{
		auto&& first=begin(container), last=end(container);
		auto&& back=prev(last);
		for(auto e=first; e!=last; e=next(e))
			cout<<*e<<" \n"[e==back];
}


extern void* enabler;
template<typename Head, typename enable_if<!has_iter<Head>::value>::type*& = enabler>
void print(const Head& head)
{
	cout<<head<<endl;
}

template<> void print<string>(const string& container)
{
	cout<<container<<endl;
}

template<typename Head, typename... Tail>
void print(const Head& head, const Tail&... tail)
{
	cout<<head<<" ";
	print(tail...);
}

void io_speedup()
{
	cin.tie(0);
	cout.tie(0);
	ios::sync_with_stdio(false);
}

template<typename T>
istream& operator >> (istream& is, vector<T>& vec)
{
	for(T& x: vec) is >> x;
	return is;
}


template<typename T, typename U>
ostream& operator << (ostream& os, const pair<T, U>& p)
{
	os<<'('<<p.first<<", "<<p.second<<')';
	return os;
}

template<typename T>
vector<T> read(int n)
{
	vector<T> t(n);
	cin>>t;
	return t;
}

template<typename T>
T read()
{
	T t;
	cin>>t;
	return t;
}

template<typename Head, typename... Tail>
struct vector_demensions
{
	using type=vector<typename vector_demensions<Tail...>::type>;
};

template<typename Head>
struct vector_demensions<Head> { using type=Head; };

template<typename T>
vector<T> make_vectors(int size, T val)
{
	return vector<T>(size, val);
}

template<typename T=int, typename... Args>
auto make_vectors(int size, Args... tail)
	-> typename vector_demensions<Args..., T>::type
{
	auto val=make_vectors<T>(forward<Args>(tail)...);
	return vector<decltype(val)>(size, val);
}

using Graph=vector<VI>;
int main()
{
	int n,m;
	cin>>n>>m;
	auto s=read<string>();
	Graph g(n);
	REP(i,m)
	{
		int a,b;
		cin>>a>>b;
		a--;b--;
		g[a].push_back(b);
		g[b].push_back(a);
	}
	vector<VB> reach(n,VB(4)), ret(n,VB(4));
	function<bool(int,int)> dfs=[&](int v,int c)
	{
		//print(v,c);
		if(reach[v][c]&&!ret[v][c])
		{
			//print(reach[v][c]?1:0, ret[v][c]?1:0);
			return true;
		}
		if(reach[v][c]&&ret[v][c])
		{
			//print(reach[v][c]?1:0, ret[v][c]?1:0);
			return false;
		}
		reach[v][c]=1;
		int c2=(c+1)%4;
		bool f=false;
		for(auto&& e:g[v])
		{
			if(c2<2)
			{
				if(s[e]!='A')
					continue;
				f|=dfs(e, c2);
			}
			else
			{
				if(s[e]!='B')
					continue;
				f|=dfs(e, c2);
			}
			if(f)
			{
				//print(v,e,c2);
				break;
			}
		}
		ret[v][c]=1;
		return f;
	};
	bool ans=0;
	REP(i,n)
	{
		if(s[i]=='A'&&!reach[i][0])
			ans|=dfs(i,0);
	}
	print(ans?"Yes":"No");
}

Measured memory_bytes: 37508