#include<map>
#include<set>
#include<queue>
#include<deque>
#include<cmath>
#include<ctime>
#include<bitset>
#include<vector>
#include<cstdio>
#include<string>
#include<cstdlib>
#include<cstring>
#include<iostream>
#include<algorithm>
#include<unordered_map>
using namespace std;
typedef long long ll;
typedef long double ld;
typedef unsigned int uint;
typedef unsigned long long ull;
#define mkp make_pair
#define lb lower_bound
#define ub upper_bound
#define eb emplace_back
#define fs fflush(stdout)
#define ump unordered_map
#define pq priority_queue
#define clz __builtin_clz
#define ctz __builtin_ctz
#define space putchar(' ')
#define enter putchar('\n')
#define sz(x) (int)x.size()
#define np next_permutation
#define clzl __builtin_clzll
#define par __builtin_parity
#define ctzl __builtin_ctzll
#define ppc __builtin_popcount
#define parl __builtin_parityll
#define all(x) x.begin(),x.end()
#define ppcl __builtin_popcountll
#define ms(x,y) memset(x,y,sizeof(x))
#define debug(x) cerr<<#x<<"= "<<(x)<<'\n'
template<class T> inline T &read(T &x){
	x=0;int f=1;char ch=getchar();
	while(ch<48||ch>57){if(ch=='-') f=-f;ch=getchar();}
	while(ch>=48&&ch<=57) x=(x<<1)+(x<<3)+(ch^48),ch=getchar();
	return x*=f;
}
template<class T> inline void print(T x){
	static char buf[40];static int cnt=0;
	if(x<0) putchar(45),x=-x;
	do buf[++cnt]=x%10^48;while(x/=10);
	do putchar(buf[cnt--]);while(cnt);
}
#define mod 998244353
#define inf 0x3f3f3f3f
#define fpi freopen("","r",stdin)
#define fpo freopen("","w",stdout)
char s[200005];
int cnt[200005],tot;
struct node{int u,v;}edge[200005];
void solve(int n,int m){
	int i;ll ans=0;tot=0;
	for(i=1;i<=n;i++) cnt[i]=0;
	scanf("%s",s+1);
	while(m--){int u=read(u),v=read(v);if(s[u]^s[v]) cnt[u]++,cnt[v]++,edge[++tot]={u,v};}
	for(i=1;i<=tot;i++) ans+=(ll)(cnt[edge[i].u]-1)*(cnt[edge[i].v]-1);print(ans),enter;
}
int main(){
	int n,m;
	while(cin>>n>>m) solve(n,m);
	return 0;
}