#pragma GCC optimize(2)

#pragma GCC optimize(3)

#pragma GCC optimize(4)

#include<bits/stdc++.h>

using namespace std;

#define fi first

#define se second

#define pi acos(-1.0)

#define LL long long

//#define mp make_pair

#define pb push_back

#define ls rt<<1, l, m

#define rs rt<<1|1, m+1, r

#define ULL unsigned LL

#define pll pair<LL, LL>

#define pii pair<int, int>

#define piii pair<pii, int>

#define mem(a, b) memset(a, b, sizeof(a))

#define fio ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);

#define fopen freopen("in.txt", "r", stdin);freopen("out.txt", "w", stout);

//head

const int N = 2e5 + ;

vector<int> g[N];

char s[N];

bool vis[N];

int d[N][];

int que[N], top = ;

int main() {

    int n, m, u, v;

    scanf("%d %d", &n, &m);

    scanf("%s", s);

    for (int i = ; i <= m; i++) {

        scanf("%d %d", &u, &v);

        g[u].pb(v);

        g[v].pb(u);

    }

    for (int i = ; i <= n; i++) {

        for (int v : g[i]) {

            d[v][s[i-] - 'A']++;

        }

    }

    for (int i = ; i <= n; i++) {

        if(!d[i][] || !d[i][]) que[++top] = i, vis[i] = true;

    }

    int now = ;

    while(now <= top) {

        int u = que[now];

        for (int v : g[u]) {

            d[v][s[u-] - 'A'] --;

            if(!vis[v] && !d[v][s[u-] - 'A']) que[++top] = v, vis[v] = true;

        }

        now++;

    }

    if(top < n) puts("Yes");

    else puts("No");

    return ;

}