#include<cstdio>
#include<queue>
#include<utility>
#include<cstring>
#include<stack>
#include<algorithm>
#include<cmath>
#include<iostream>
#define MAX_N 100001
#define INF 2147483647
#define REP(i,n) for(int i=0;i<(int)(n);i++)
void init(int n);
int find(int n);
void unite(int x,int y);
bool same(int x, int y);
int dx[4] = {1,0,0,-1};
int dy[4] = {0,1,-1,0};
using namespace std;

struct edge{
  int from,to;
};
typedef vector<vector<edge> > AdjList;
typedef long long ll;
typedef pair<int , int> P;
long long int MOD = 1000000007;
long long int ruiseki[200001];
int ncrset(){
  ruiseki[0] = 1;
  for(int i=1;i<200001;i++){
    ruiseki[i] = (ruiseki[i-1] * i) % MOD;
  }
}

long long int powld(long long int x,long long int n){
  long long int ans = 1;
  while(n > 0){
    if((n&1) == 1){
      ans = (ans*x)  % MOD;
    }
    x = (x*x) % MOD;
    n >>= 1;
  }
  return ans % MOD;
}

ll ncrgyaku(ll n,ll r){
  long long int gyakuk,gyakur;
  long long int res = 1,x,y,z;
  y = powld(ruiseki[r],MOD-2);
  z = powld(ruiseki[n-r],MOD-2);
  return (((ruiseki[n]*y) % MOD)*z) % MOD;

}

vector< vector<ll> > graph[4];
ll N,M,u,v;
string S;
ll memo[100001];

ll solve(int n,int LEVEL){
  if(memo[n] != -1)
    return memo[n];
  if(LEVEL == 3){
    return memo[n] = 1;
  }
  LEVEL++;
  ll res=0;
  for(int i=0;i<graph[LEVEL][n].size();i++){
    res = (res+solve(graph[LEVEL][n][i],LEVEL))%MOD;
  }
  return memo[n] = res;
}

int main()
{
  REP(i,100001){
    memo[i] = -1;
  }
  cin >> N >> M;
  cin >> S;
  REP(i,4)
    graph[i] = vector<vector<ll> >(N,vector<ll>(0));
  REP(i,M){
    cin >> u >> v;
    u--;v--;
    if(S[u] == 'P'){
      graph[0][v].push_back(u);
    }else if(S[u] == 'D'){
      graph[1][v].push_back(u);
    }else if(S[u] == 'C'){
      graph[2][v].push_back(u);
    }else{
      graph[3][v].push_back(u);
    }

    if(S[v] == 'P'){
      graph[0][u].push_back(v);
    }else if(S[v] == 'D'){
      graph[1][u].push_back(v);
    }else if(S[v] == 'C'){
      graph[2][u].push_back(v);
    }else{
      graph[3][u].push_back(v);
    }
  }
  ll res = 0;
  for(int i=0;i<S.size();i++){
    if(S[i] == 'P'){
      res = (res+ solve(i,0))%MOD;
    }
  }
  cout << res << endl;
    
  return 0;
}

int par[MAX_N];
int ranks[MAX_N];

//n要素で初期化
void init(int n){
  REP(i,n){
    par[i] = i;
    ranks[i] = 0;
  }

}

//木の根を求める
int find(int x){
  if(par[x] == x){
    return x;
  }else{
    return par[x] = find(par[x]);
  }
}

void unite(int x,int y){
  x = find(x);
  y = find(y);
  if(x == y) return ;
  if(ranks[x] < ranks[y]){
    par[x] = y;
  }else{
    par[y] = x;
    if(ranks[x] == ranks[y]) ranks[x]++;
  }
}

bool same(int x, int y){
  return find(x) == find(y);
}