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

void speed()
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);
}

int n;
string s;
int dp[100001];

int solve()
{
    speed();
    cin>>n;
	cin>>s;
    dp[0]=1;
    for(int i=1; i<n; i++)
    {
        if(s[i] >= s[i-1])
        {
            dp[i]=dp[i-1];
        }
        else dp[i]=dp[i-1]+1;

    }
    return dp[n-1]-1;
}

int main()
{
    freopen("freddy.in", "r", stdin);
    freopen("freddy.out", "w", stdout);
    cout<<solve()<<endl;
    return 0;
}