#include <stdio.h>
#include <string.h>
#include <algorithm>
#include <iostream>
#include <string>
#include <vector>
#include <functional>
#include <map>
#include <iomanip>
#include <math.h> 
#include <stack>
#include <queue>
#include <bitset>
#include <cstdlib>
#include <tuple>
#include <cctype>
#include <ctype.h>
#include <set>
#include <sstream>
#include <time.h>
using namespace std;
//#define int long long
#define rep(i,s,n) for(int i = s;i<n;i++)
#define repe(i,s,n) for(int i = s;i<=n;i++)
#define rrep(i,s,n) for(int i = (n)-1;i>=(s);i--)
#define all(v) (v).begin(),(v).end()
#define pb push_back
#define fi first
#define se second
#define chmin(a,b) a=min((a),(b))
#define chmax(a,b) a=max((a),(b))
typedef long long ll;
typedef pair<int, int>pint;
typedef vector<int>vint;
typedef vector<pint>vpint;
typedef pair<pint, int> P1;
typedef pair<int, pint> P2;
typedef pair<pint, pint> PP;
static const ll maxLL = (ll)1 << 62;
const ll MOD = 1000000007;
const ll INF = 1e18;
int ca[12] = { 31,28,31,30,31,30,31,31,30,31,30,31 };

int n, m, cnt = 0;
string s;
vector<int>plist, dlist, clist, alist;

struct MyStruct
{
	char ch;
	int no;
	vector<int>ren;
};

vector<MyStruct>list(100005);

int funcC(int index) {

	for (int i = 0; i < list[index].ren.size(); i++) {
		if (list[list[index].ren[i]].ch == 'A') {
			cnt++;
			cnt %= MOD;
		}
	}


	return 0;
}

int funcD(int index) {

	for (int i = 0; i < list[index].ren.size(); i++) {
		if (list[list[index].ren[i]].ch == 'C') {
			funcC(list[index].ren[i]);
		}
	}


	return 0;
}


int funcP(int index) {

	for (int i = 0; i < list[index].ren.size(); i++) {
		if (list[list[index].ren[i]].ch == 'D') {
			funcD(list[index].ren[i]);
		}
	}


	return 0;
}





signed main() {
	int i, j;
	

	cin >> n >> m;
	cin >> s;


	for (i = 0; i < m; i++) {
		int num1, num2;
		cin >> num1 >> num2;

		list[num1].ren.push_back(num2);
		list[num2].ren.push_back(num1);
	}

	for (i = 0; i < n; i++) {
		list[i + 1].ch = s[i];
		unique(list[i].ren.begin(), list[i].ren.end());
	}


	for (i = 1; i <= n; i++) {
		if (list[i].ch == 'P') {
			funcP(i);
		}
	}



	cout << cnt << endl;









	getchar();
	getchar();
	return 0;
}