#include<bits/stdc++.h>
#define ii          int int
#define ll       	long long
#define pi       	pair<int,int>
#define pl       	pair<ll,ll>
#define ps       	pair<string,string>
#define mod      	1000000007
#define INF      	1e18
#define PI       	acos(-1)
#define si(a)    	scanf("%d",&a)
#define ss(a)           scanf("%s",a);
#define sii(a,b)  	scanf("%d%d",&a,&b)
#define siii(a,b,c)     scanf("%d%d%d",&a,&b,&c)
#define sl(a)    	scanf("%lld",&a)
#define sL(a)    	scanf("%I64d",&a)
#define sll(a,b) 	scanf("%lld%lld",&a,&b)
#define sLL(a,b)        scanf("%I64d%I64d",&a,&b)
#define slll(a,b,c)     scanf("%lld%lld%lld",&a,&b,&c)
#define sLLL(a,b,c)    scanf("%I64d%I64d%I64d",&a,&b,&c)

//geometry
#define EPS 1e-12
#define _abs(x)    (((x)>0)?(x):-(x))
#define _max(x,y)  ( ((x)>(y))?(x):(y))
#define _min(x,y)  ( ((x)<(y))?(x):(y))

#define E(x,y)	(_abs((x)-(y)) < EPS)
#define Z(x)	(_abs(x) < EPS)
#define ZN(x)	(x < 0 || Z(x))
#define ZP(x)	(x > 0 || Z(x))

//END
#define FR(i,a,b) 	for(ll i=(a);i<(b);i++)
#define F       	first
#define S        	second
#define pb       	push_back

#define mp       	make_pair
#define bg       	begin()
#define en       	end()
#define mem(a,b) 	memset(a,b,sizeof(a))
#define vsort(v)        sort(v.begin(),v.end())
#define REV(v)         reverse(v.begin(),v.end())
#define RET            return(0)
#define  _               ios_base::sync_with_stdio(0);cin.tie(0);
using namespace std;
int digit,small,big,special;
int main()
{
    int n;
    si(n);
    string s;
    cin>>s;
    for(int i=0;i<s.size();i++)
    {
        if(isdigit(s[i]))digit=1;
        else if(isupper(s[i]))big=1;
        else if(islower(s[i]))small=1;
        else special=1;
    }
    int aa=digit+big+small+special;
    int sz=(int)s.size();
    if(aa==4&&sz>=6)
    {
        puts("0");
        RET;
    }
    else if(aa==4&&sz<6)
    {
        printf("%d\n",6-sz);
        RET;
    }
    else if(aa<4&&sz>=6)
    {
        printf("%d\n",4-aa);
        RET;
    }
    else if(aa<4&&sz<6)
    {
        printf("%d\n",max(6-sz,4-aa));
        RET;
    }
}