#pragma GCC optimize("Ofast")

#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
typedef pair<ld,ld> pdd;

#define X first
#define Y second

//#include <boost/unordered_map.hpp>
//using namespace boost;

/*
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/pb_ds/assoc_container.hpp>
using namespace __gnu_pbds;
typedef tree<int, null_type, less<int>, rb_tree_tag, tree_order_statistics_node_update> rbtree;
rbtree T;
*/

namespace io{
	const int L = (1 << 20) + 1;
	
	char buf[L], *S , *T, c;
	 
	char getchar() {
		if(__builtin_expect(S == T, 0)) {
			T = (S = buf) + fread(buf, 1, L, stdin);
			return (S == T ? EOF : *S++);
		}
		return *S++;
	}
	
	int inp() {
		int x = 0, f = 1; char ch;
		for(ch = getchar(); !isdigit(ch); ch = getchar())
			if(ch == '-') f = -1;
		for(; isdigit(ch); x = x * 10 + ch - '0', ch = getchar());
		return x * f;
	}
	
	unsigned inpu()
	{
		unsigned x = 0; char ch;
		for(ch = getchar(); !isdigit(ch); ch = getchar());
		for(; isdigit(ch); x = x * 10 + ch - '0', ch = getchar());
		return x;
	}
	
	ll inp_ll() {
		ll x = 0; int f = 1; char ch;
		for(ch = getchar(); !isdigit(ch); ch = getchar())
			if(ch == '-') f = -1;
		for(; isdigit(ch); x = x * 10 + ch - '0', ch = getchar());
		return x * f;
	}
	
	char B[25], *outs=B+20, *outr=B+20;
	template<class T>
	inline void print(register T a,register char x=0){
		if(x) *--outs = x, x = 0;
		
		if(!a)*--outs = '0';
		else 
			while(a)
				*--outs = (a % 10) + 48, a /= 10;
		
		if(x)
			*--outs = x;
		
		fwrite(outs, outr - outs , 1, stdout);
		outs = outr;
	}
};

using io :: print;
using io :: inp;
using io :: inpu;
using io :: inp_ll;

using i32 = int;
using i64 = long long;
using u8 = unsigned char;
using u32 = unsigned;
using u64 = unsigned long long;
using f64 = double;
using f80 = long double;

ll power(ll a, ll b, ll p)
{
	if (!b) return 1;
	ll t = power(a, b/2, p);
	t = t*t%p;
	if (b&1) t = t*a%p;
	return t;
}

const int MAXN = 200010;
const u64 MOD = 1000000007;
const f80 MI = f80(1)/MOD;
const int INF = 1000000010;

int n, m;
int a[MAXN], alive[MAXN];
vector<int> v[MAXN];
char s[MAXN];
int b[MAXN], tb[MAXN];
int u[MAXN];

int main()
{
	
	scanf("%d%d", &n, &m);
	scanf("%s", s+1);
	for (int i = 1; i <= m; ++ i)
	{
		int x, y;
		scanf("%d%d", &x, &y);
		v[x].push_back(y);
		v[y].push_back(x);
	}
	
	queue<int> Q;
	for (int i = 1; i <= n; ++ i)
	{
		alive[i] = 1;
		for (auto j : v[i])
		{
			if (s[j] == 'A') a[i] ++;
			if (s[j] == 'B') b[i] ++;
		}
		if (!a[i] || !b[i])
		{
			alive[i] = 0;
			Q.push(i);
		}
	}
	while (!Q.empty())
	{
		int x = Q.front();
		Q.pop();
		for (auto y : v[x])
		{
			if (!alive[y]) continue;
			if (s[x] == 'A') a[y] --;
			if (s[x] == 'B') b[y] --;
			if (a[y] == 0 || b[y] == 0)
			{
				alive[y] = 0;
				Q.push(y);
			}
		}
	}
	
	int flag = 0;
	for (int i = 1; i <= n; ++ i)
		if (alive[i]) flag = 1;
	puts(flag ? "Yes" : "No");
	/*
	for (int i = 1; i <= n; ++ i)
	{
		if (u[i]) continue;
		if (!alive[i]) continue;
		queue<int> Q;
		int flag = 0;
		Q.push(i);
		while (!Q.empty())
		{
			int x = Q.front();
			Q.pop();
			if (s[x] == 'A') flag |= 1;
			if (s[x] == 'B') flag |= 2;
			for (auto y : v[x])
				if (alive[y] && !u[y])
				{
					u[y] = 1;
					Q.push(y);
				}
		}
		if (flag == 3)
		{
			puts("Yes");
			return 0;
		}
	}
	puts("No");
	*/
	return 0;
}


Measured memory_bytes: 13184