import sys
sys.setrecursionlimit(10**7)
N, M = map(int, input().split())
S = input()
G = [list(map(int, input().split())) for _ in range(M)]
edges = [[] for _ in range(N)]
for a, b in G:
    edges[a - 1].append(b - 1)
    edges[b - 1].append(a - 1)
def dfs(start,path):
    ans = 0
    check = 'PDCA'
    path.append(S[start])
    for i in range(min(4,len(path))):
        if path[i] != check[i]:
            path.pop()
            return 0
    if ''.join(path) == 'PDCA':
        path.pop()
        return 1
    elif len(path) > 4:
        path.pop()
        return 0
    for i in edges[start]:
        ans += dfs(i,path)
    path.pop()
    return ans
ans = 0
for i in range(N):
    ans += dfs(i,[])
print(ans)