import std.stdio, std.string, std.conv;
import std.range, std.algorithm, std.array, std.typecons, std.container;
import std.math, std.numeric, core.bitop;

enum mod = 10^^9 + 7;

void main() {
    int[char] cnv = ['P':0, 'D':1, 'C':2, 'A':3];
    int n, m;
    scan(n, m);
    auto s = readln.chomp.map!(ch => cnv[ch.to!char]).array;
    auto adj = new int[][](n, 0);

    foreach (i ; 0 .. m) {
        int ui, vi;
        scan(ui, vi);
        ui--, vi--;
        if (s[ui] > s[vi]) {
            swap(ui, vi);
        }
        if (s[vi] - s[ui] == 1) {
            adj[vi] ~= ui;
        }
    }

    auto dp = new int[](n);
    dp[] = -1;

    int dfs(int v) {
        if (s[v] == 0) {
            return dp[v] = 1;
        }
        if (dp[v] != -1) {
            return dp[v];
        }
        dp[v] = 0;
        foreach (u ; adj[v]) {
            dp[v] += dfs(u);
            dp[v] %= mod;
        }
        return dp[v];
    }

    int ans;

    foreach (i ; 0 .. n) {
        if (dp[i] == -1) {
            dfs(i);
        }
        if (s[i] == 3) {
            ans += dp[i];
            ans %= mod;
        }
    }

    writeln(ans);
}































void scan(T...)(ref T args) {
    import std.stdio : readln;
    import std.algorithm : splitter;
    import std.conv : to;
    import std.range.primitives;

    auto line = readln().splitter();
    foreach (ref arg; args) {
        arg = line.front.to!(typeof(arg));
        line.popFront();
    }
    assert(line.empty);
}

void fillAll(R, T)(ref R arr, T value) {
    static if (is(typeof(arr[] = value))) {
        arr[] = value;
    }
    else {
        foreach (ref e; arr) {
            fillAll(e, value);
        }
    }
}