#include <iostream>
#include <cstring>
#include <cstdio>
#include <algorithm>
#include <cmath>
#include <vector>
#include <list>
#include <utility>
#include <iterator>
#include <map>
#include <stack>
#include <queue>
#include <set>
#include <deque>
#include <bitset>
#include <complex>
#include <iomanip>
#include <assert.h>
//#include <ext/pb_ds/assoc_container.hpp>
//#include <ext/pb_ds/tree_policy.hpp>

//#include <unordered_set>
#include <unordered_map>


#define mod 1000000007
#define mod2 1000000009
#define mod1 1432344041
#define ima 1000000004

#define imi -1000000004
#define llma 1000000000000000004
#define llmi -1000000000000000004
#define lp(i,n) for(i=0;i<n;i++)
#define li(i,n) for(i=n-1;i>=0;i--)
#define ll long long int
#define ld long double
#define f first
#define s second
#define pa pair<ll,ll>
#define pad pair<ld ,ld>
#define pai pair<int,int>
#define pal pair<int,ll>
#define pai3 pair< pair<ll,int>,pai >
#define mp make_pair
#define nn 300005
#define pi 3.1415926535898
#define inf 1e-10
#define diff 1e-15
#define pb push_back
#define sync ios::sync_with_stdio(false);cout.tie(0);cin.tie(0);
#define lc(a) 2*a+1
#define rc(a) 2*a+2
#define h1 47
#define h2 101mp
#define mod3 999347
#define mod4 107729
#define N 1200005
#define lgN 23
#define BLK 320
#define endl '\n'

#define RTIME ((double)clock()/(double)CLOCKS_PER_SEC)



using namespace std;

typedef complex<double> base;
template<class T> using max_pq = priority_queue<T>;
template<class T> using min_pq = priority_queue<T,vector<T>,greater<T>>;

ll x,y;
template<class T> T gcd(T a,T b){if(a==0) {x=0,y=1; return b;}T gc=gcd(b%a,a);T temp;temp=x;x=y-(b/a)*temp;y=temp;return gc;}//y is the inverse and a is modulus and define x & y

ll po(ll a, ll x,ll m){ if(x==0){return 1;}ll ans=1;ll k=1;  while(k<=x) {if(x&k){ans=((ans*a)%m);} k<<=1; a*=a; a%=m; }return ans; } //(a^x)%m


int mark[5];

int main()
{
    sync
    int n;
    cin>>n;
    string s;
    cin>>s;
    for(int i=0;i<n;i++)
    {
        if(s[i]>='A' && s[i]<='Z')
            mark[0]=1;
        else if(s[i]>='a' && s[i]<= 'z')
            mark[1]=1;
        else if(s[i]>='0' && s[i]<='9')
            mark[2]=1;
        else
            mark[3]=1;
    }
    int a = mark[0]+mark[1]+mark[2]+mark[3];
    int b = 6-n;
    a = 4-a;
    cout<<max(a,b)<<endl;
}