n=int(input())
s=input()
ans=(n-1)*n//2
ab=0
for _ in range(2):
con=1
for i in range(n-1):
if s[i]==s[i+1]:
con+=1
else:
ans-=con
con=1
ab+=1
s=s[::-1]
print(ans+ab//2)#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define ull unsigned long long
#define pb push_back
#define foru(i,a,b) for(int i = a; i <= b; i++)
#define ford(i,a,b) for(int i = a; i >= b; i--)
#define fi first
#define se second
#define endl "\n"
typedef pair<ll,ll> ii;
typedef vector<ii> vii;
const int maxn = 3e5 + 7;
const int oo = 1e9 + 7;
const int MOD = 1e9 + 7;
const int block_size = 750;
void init() {
if(fopen("1238D.inp", "r")) {
freopen("1238D.inp","r",stdin);
freopen("1238D.out","w",stdout);
}
ios_base::sync_with_stdio(0);
cin.tie(NULL);
cout.tie(NULL);
}
int main() {
init();
int n; string str;
cin >> n >> str;
ll sub = 0;
for(int i = 0; i < n; i++) {
for(int j = i + 1; j < n && str[j] != str[i]; j++) sub++;
for(int j = i - 1; j >= 0 && str[j] != str[i]; j--) sub++;
if(i > 0 && str[i - 1] != str[i]) sub--;
// cout << i << ' ' << sub << endl;
}
ll res = 1ll * n * (n - 1) / 2 - sub;
cout << res;
}
1711A - Perfect Permutation | 1701B - Permutation |
1692A - Marathon | 1066A - Vova and Train |
169B - Replacing Digits | 171D - Broken checker |
380C - Sereja and Brackets | 1281B - Azamon Web Services |
1702A - Round Down the Price | 1681C - Double Sort |
12A - Super Agent | 1709A - Three Doors |
1680C - Binary String | 1684B - Z mod X = C |
1003A - Polycarp's Pockets | 1691B - Shoe Shuffling |
1706A - Another String Minimization Problem | 1695B - Circle Game |
1702B - Polycarp Writes a String from Memory | 1701A - Grass Field |
489C - Given Length and Sum of Digits | 886B - Vlad and Cafes |
915A - Garden | 356A - Knight Tournament |
1330A - Dreamoon and Ranking Collection | 1692B - All Distinct |
1156C - Match Points | 1675A - Food for Animals |
1328C - Ternary XOR | 1689A - Lex String |