#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];
int d[N];
PII edge[N];
int cnt;
int n,m,res;

void solve()
{
	while(cin>>n>>m)
	{
		cin>>(s+1);
		cnt=res=0;
		for(int i=1;i<=n;i++)
			d[i]=0;
		while(m--)
		{
			int a,b;
			cin>>a>>b;
			if(s[a]!=s[b])
			{
				d[a]++,d[b]++;
				edge[cnt++]={a,b};
			}
		}
		for(int i=0;i<cnt;i++)
			res+=(d[edge[i].x]-1)*(d[edge[i].y]-1);
		cout<<res<<endl;
	}
	
	return ;
}

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