using System;
using System.Linq;
using System.Collections.Generic;

namespace Contest
{
    class Program
    {
        static void Main(string[] args)
        {
            AGC027.C();
        }

        class AGC027
        {
            public static void A()
            {
                var N = Read.Int();
                var X = Read.Long();
                var A = Read.LongN();
                Array.Sort(A);
                var Asum = Util.ASum(A);
                int max = 0;
                for(int i = 1; i < N; ++i)
                {
                    if (Asum[i] <= X) { max = i; }
                }
                Console.WriteLine(Asum[N] == X ? N : max);
            }
            public static void C()
            {
                var N = Read.Int();
                var M = Read.Int();
                var S = Read.Str();
                Dictionary<int, HashSet<int>> Adj = new Dictionary<int, HashSet<int>>();
                for (int i = 0; i <= N; ++i)
                {
                    Adj.Add(i, new HashSet<int>());
                }
                for (int i = 0; i < M; ++i)
                {
                    var ab = Read.IntN();
                    var a = ab[0];
                    var b = ab[1];
                    if (!Adj[a].Contains(b)) { Adj[a].Add(b); }
                    if (!Adj[b].Contains(a)) { Adj[b].Add(a); }
                }
                int[] AdjA = new int[N + 1];
                int[] AdjB = new int[N + 1];
                for(int i = 1; i <= N; ++i)
                {
                    var isA = S[i - 1] == 'A';
                    foreach(var w in Adj[i])
                    {
                        (isA ? AdjA : AdjB)[w]++;
                    }
                }
                bool[] removed = new bool[N + 1];
                Queue<int> queue = new Queue<int>();
                for (int i = 1; i <= N; ++i)
                {
                    if(AdjA[i] == 0 || AdjB[i] == 0) { queue.Enqueue(i); removed[i] = true; }
                }
                while (queue.Count > 0)
                {
                    var v = queue.Dequeue();
                    var isA = S[v - 1] == 'A';
                    foreach(var w in Adj[v])
                    {
                        if (!removed[w])
                        {
                            (isA ? AdjA : AdjB)[w]--;
                            if (AdjA[w] == 0 || AdjB[w] == 0) { queue.Enqueue(w);removed[w] = true; }
                        }
                    }
                }
                Console.WriteLine(removed.Skip(1).Contains(false) ? "Yes" : "No");
            }
        }


        class Util
        {
            public static long[] ASum(long[] array)
            {
                var res = new long[array.Length + 1];
                for (int i = 0; i < array.Length; ++i)
                {
                    res[i + 1] = res[i] + array[i];
                }
                return res;
            }
            public static long GCD(long a, long b)
            {
                while (b > 0)
                {
                    var c = a % b;
                    a = b;
                    b = c;
                }
                return a;
            }
        }


        static class Read
        {
            static Queue<string> queue = new Queue<string>();
            static void Enqueue() { var ss = Console.ReadLine().Split(' '); foreach (var s in ss) { queue.Enqueue(s); } }
            public static int Int() { if (queue.Count == 0) { Enqueue(); } return Convert.ToInt32(queue.Dequeue()); }
            public static long Long() { if (queue.Count == 0) { Enqueue(); } return Convert.ToInt64(queue.Dequeue()); }
            public static string Str() { if (queue.Count == 0) { Enqueue(); } return queue.Dequeue(); }
            public static int[] IntN() { return Console.ReadLine().Split(' ').Select(s => Convert.ToInt32(s)).ToArray(); }
            public static long[] LongN() { return Console.ReadLine().Split(' ').Select(s => Convert.ToInt64(s)).ToArray(); }
            public static string[] StrN() { return Console.ReadLine().Split(' '); }
            public static Tuple<int, int>[] TupleInt(int n) { List<Tuple<int, int>> list = new List<Tuple<int, int>>(); for (int i = 0; i < n; ++i) { var ab = Read.IntN(); list.Add(new Tuple<int, int>(ab[0], ab[1])); } return list.ToArray(); }
            public static Tuple<long, long>[] TupleLong(int n) { List<Tuple<long, long>> list = new List<Tuple<long, long>>(); for (int i = 0; i < n; ++i) { var ab = Read.LongN(); list.Add(new Tuple<long, long>(ab[0], ab[1])); } return list.ToArray(); }
            public static Tuple<string, string>[] TupleStr(int n) { List<Tuple<string, string>> list = new List<Tuple<string, string>>(); for (int i = 0; i < n; ++i) { var ab = Read.StrN(); list.Add(new Tuple<string, string>(ab[0], ab[1])); } return list.ToArray(); }
            public static Tuple<double, double>[] TupleDouble(int n) { List<Tuple<double, double>> list = new List<Tuple<double, double>>(); for (int i = 0; i < n; ++i) { var ab = Read.LongN(); list.Add(new Tuple<double, double>(ab[0], ab[1])); } return list.ToArray(); }
            public static long[,] LongMatrix(int r, int c)
            {
                var mat = new long[r, c];
                for (int i = 0; i < r; ++i)
                {
                    var x = Read.LongN();
                    for (int j = 0; j < c; ++j)
                    {
                        mat[i, j] = x[j];
                    }
                }
                return mat;
            }
            public static Dictionary<int, HashSet<int>> AdjacencyList(int N, int M)
            {
                Dictionary<int, HashSet<int>> dict = new Dictionary<int, HashSet<int>>();
                for (int i = 0; i <= N; ++i)
                {
                    dict.Add(i, new HashSet<int>());
                }
                for (int i = 0; i < M; ++i)
                {
                    var ab = Read.IntN();
                    dict[ab[0]].Add(ab[1]);
                    dict[ab[1]].Add(ab[0]);
                }
                return dict;
            }
            public static Dictionary<int, Dictionary<int, long>> AdjacencyListWithWeight(int N, int M)
            {
                Dictionary<int, Dictionary<int, long>> dict = new Dictionary<int, Dictionary<int, long>>();
                for (int i = 0; i <= N; ++i)
                {
                    dict.Add(i, new Dictionary<int, long>());
                }
                for (int i = 0; i < M; ++i)
                {
                    var ab = Read.IntN();
                    dict[ab[0]].Add(ab[1], ab[2]);
                    dict[ab[1]].Add(ab[0], ab[2]);
                }
                return dict;
            }
        }
    }
}


Measured memory_bytes: 63136