#define _USE_MATH_DEFINES
#include <bits/stdc++.h>
using namespace std;
typedef long long LL;
typedef unsigned long long ULL;

template <typename T1, typename T2>
string print_iterable(T1 begin_iter, T2 end_iter, int counter) {
    bool done_something = false;
    stringstream res;
    res << "[";
    for (; begin_iter != end_iter and counter; ++begin_iter) {
        done_something = true;
        counter--;
        res << *begin_iter << ", ";
    }
    string str = res.str();
    if (done_something) {
        str.pop_back();
        str.pop_back();
    }
    str += "]";
    return str;
}

vector<int> SortIndex(int size, std::function<bool(int, int)> compare) {
    vector<int> ord(size);
    for (int i = 0; i < size; i++) ord[i] = i;
    sort(ord.begin(), ord.end(), compare);
    return ord;
}

template <typename T>
bool MinPlace(T& a, const T& b) {
    if (a > b) {
        a = b;
        return true;
    }
    return false;
}

template <typename T>
bool MaxPlace(T& a, const T& b) {
    if (a < b) {
        a = b;
        return true;
    }
    return false;
}

template <typename Container>
int SZ(const Container& S) { return S.size(); }

template <typename S, typename T>
ostream& operator <<(ostream& out, const pair<S, T>& p) {
    out << "{" << p.first << ", " << p.second << "}";
    return out;
}

template <typename T>
ostream& operator <<(ostream& out, const vector<T>& v) {
    out << "[";
    for (int i = 0; i < (int)v.size(); i++) {
        out << v[i];
        if (i != (int)v.size()-1) out << ", ";
    }
    out << "]";
    return out;
}

#if DEBUG && !ONLINE_JUDGE
    ifstream input_from_file("input.txt");
    #define cin input_from_file

    #define dbg_var(x) clog << #x  << ": " << x << endl;
    #define dbg_array(x, len) clog << #x << ": " << print_iterable(x, x+len, -1) << endl;
#else
    #define dbg_var(x)
    #define dbg_array(x, len)
#endif

///////////////////////////////////////////////////////////////////////////
//////////////////// DO NOT TOUCH BEFORE THIS LINE ////////////////////////
///////////////////////////////////////////////////////////////////////////

const int MAXN = 220000;

vector<int> aa[MAXN];
int main() {
    ios::sync_with_stdio(false);
    cin.tie(0); // Remove in problems with online queries!
    int N, M;
    string S;

    cin >> N >> M;
    cin >> S;
    vector<int> nearA(N, 0), nearB(N, 0);
    for (int i = 0; i < M; i++) {
        int x, y;
        cin >> x >> y;
        x--, y--;
        aa[x].push_back(y);
        aa[y].push_back(x);
        if (S[x] == 'A') nearA[y]++;
        else nearB[y]++;
        if (S[y] == 'A') nearA[x]++;
        else nearB[x]++;
    }
    // dbg_var(nearA);
    // dbg_var(nearB);
    vector<bool> tolto(N, false);
    int cnt = 0;
    queue<int> q;
    for (int i = 0; i < N; i++) {
        if (nearA[i] == 0 or nearB[i] == 0) {
            tolto[i] = true;
            q.push(i);
            cnt++;
        }
    }
    // dbg_var(tolto);
    while (!q.empty()) {
        int v = q.front();
        q.pop();
        for (int a : aa[v]) {
            // cout << a << " " << v << endl;
            if (S[v] == 'A') nearA[a]--;
            else nearB[a]--;
            if (!tolto[a] and (nearA[a] == 0 or nearB[a] == 0)) {
                tolto[a] = true;
                q.push(a);
                cnt++;
            }
        }
    }

    cout << ((cnt < N)?"Yes":"No") << "\n";
}


Measured memory_bytes: 12880