#include <iostream>
#include <algorithm>
#include <vector>
#include <set>
using namespace std;
template<class T> inline void YES(T condition){ if(condition) cout << "YES" << endl; else cout << "NO" << endl; }
template<class T> inline void Yes(T condition){ if(condition) cout << "Yes" << endl; else cout << "No" << endl; }
template<class T> inline void POSS(T condition){ if(condition) cout << "POSSIBLE" << endl; else cout << "IMPOSSIBLE" << endl; }
template<class T> inline void Poss(T condition){ if(condition) cout << "Possible" << endl; else cout << "Impossible" << endl; }
template<class T> inline void First(T condition){ if(condition) cout << "First" << endl; else cout << "Second" << endl; }
template<class T = string, class U = char>int character_count(T text, U character){ int ans = 0; for(U i: text){ ans += (i == character); } return ans; }
long power(long base, long exponent, long module){ if(exponent % 2){ return power(base, exponent - 1, module) * base % module; }else if(exponent){ long root_ans = power(base, exponent / 2, module); return root_ans * root_ans % module; }else{ return 1; }}
struct position{ int y, x; }; position move_pattern[4] = {{-1, 0}, {0, 1}, {1, 0}, {0, -1}}; // double euclidean(position first, position second){ return sqrt((second.x - first.x) * (second.x - first.x) + (second.y - first.y) * (second.y - first.y)); }
template<class T, class U> string to_string(pair<T, U> x){ return to_string(x.first) + "," + to_string(x.second); }
template<class itr> void array_output(itr start, itr goal){ string ans; for(auto i = start; i != goal; i++){ ans += to_string(*i) + " "; } ans.pop_back(); cout << ans << endl; }
template<class itr> void cins(itr start, itr goal){ for(auto i = start; i != goal; i++){ cin >> (*i); } }
template<class T> T gcd(T a, T b){ if(a && b){ return gcd(min(a, b), max(a, b) % min(a, b)); }else{ return a; }} template<class T> T lcm(T a, T b){ return a / gcd(a, b) * b; }
#define mod long(998244353)
#define all(x) (x).begin(), (x).end()
#define bitcount(n) __builtin_popcountl(long(n))
#define fcout cout << fixed << setprecision(10)
#define highest(x) (63 - __builtin_clzl(x))

int N, M;
string s;
vector<vector<int>> roads;
vector<set<int>> opposite_A, opposite_B;

vector<bool> is_deleted;

void dfs(int now){
    if(is_deleted[now]){
        return;
    }
    if(opposite_A[now].empty() || opposite_B[now].empty()){
        is_deleted[now] = true;
        for(auto i: roads[now]){
            opposite_A[i].erase(now);
            opposite_B[i].erase(now);
            dfs(i);
        }
    }
}

int main(){
    cin >> N >> M >> s;
    opposite_A.resize(N);
    opposite_B.resize(N);
    roads.resize(N);
    for(int i = 0; i < M; i++){
        int a, b;
        cin >> a >> b;
        roads[a - 1].push_back(b - 1);
        if(s[b - 1] == 'A'){
            opposite_A[a - 1].insert(b - 1);
        }else{
            opposite_B[a - 1].insert(b - 1);
        }
        roads[b - 1].push_back(a - 1);
        if(s[a - 1] == 'A'){
            opposite_A[b - 1].insert(a - 1);
        }else{
            opposite_B[b - 1].insert(a - 1);
        }
    }
    is_deleted.resize(N, false);
    for(int i = 0; i < N; i++){
        dfs(i);
    }
    for(int i = 0; i < N; i++){
        if(!is_deleted[i]){
            cout << "Yes" << endl;
            return 0;
        }
    }
    cout << "No" << endl;
}


Measured memory_bytes: 45828