#include<bits/stdc++.h>
using namespace std;

#define int long long
#define endl '\n'
#define PII pair<int,int>
#define x first
#define y second
#define INF 0x3f3f3f3f

const int N=2e5+10,M=2*N,mod=1e9+7;

char s[N];
vector<int> e[N];
int d[N];
int n,m,res;

int check(int u)
{
	int cnt=0;
	for(int i:e[u])
		if(s[i]=='o'&&i!=u)
			for(int j:e[i])
				if(s[j]=='b'&&j!=u&&j!=i)
					for(int k:e[j])
						if(s[k]=='o'&&k!=i&&k!=j&&k!=u)
							cnt++;
	return cnt;
}

void solve()
{
	while(cin>>n>>m)
	{
		cin>>(s+1);
		res=0;
		while(m--)
		{
			int a,b;
			cin>>a>>b;
			e[a].push_back(b);
			e[b].push_back(a);
		}
		
		for(int i=1;i<=n;i++)
			if(s[i]=='b')
				res+=check(i);
		
		cout<<res<<endl;
		
		for(int i=1;i<=n;i++)
			e[i].clear();
	}
	
	return ;
}

signed main()
{
	ios::sync_with_stdio(false);
	cin.tie(0),cout.tie(0);
	
	int T=1;
	//cin>>T;
	while(T--)
		solve();
	
	return 0;
}