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

using i32 = int32_t;
using i64 = int64_t;
#define i128 __int128_t
using u32 = uint32_t;
using u64 = uint64_t;
using f64 = long double;

template<class T>
using lque = priority_queue<T, vector<T>, greater<T>>;
// -------------------
con i32 MX = 2e5 + 7;

i32 n, m, ct;
string inp;
i32 cnt[MX];
array<i32, 2> egs[MX];

void solve() {
    i64 ans = 0;
    for(i32 i=0; i<ct; ++i) {
        auto [u, v] = egs[i];
        ans += i64(cnt[u]-1) * (cnt[v]-1);
    }
    cout << ans;
}

void pre() {
    if(cin >> n >> m >> inp) {
        ct = 0;
        fill(cnt, cnt+n, 0);
        for(i32 i=0, u, v; i<m; ++i) {
            cin >> u >> v; --u; --v;
            if(inp[u]!=inp[v]) {
                egs[ct++] = {u, v};
                ++cnt[u];
                ++cnt[v];
            }
        }
    } else exit(0);
}

void aft() {
    cout << '\n';
}

u32 _t = -1;
void init() {
    ios::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);
    // cin >> _t;
}

int main() {
    init();
    for(u32 i=1; i<=_t;) {
        pre(); solve();
        ++i<=_t?aft():exit(0);
    }
}