#include <math.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <assert.h>
#include <limits.h>
#include <stdbool.h>

int minimumNumber(int n, char* p) {
    int c1=0,c2=0,c3=0,c4=0,i=0,c5=0,nn=strlen(p);
    
    while(p[i])
    {
        if(p[i]>='a'&&p[i]<='z')
        {
            c1=1;
        }
        if(p[i]>='A'&&p[i]<='Z')
        {
            c2=1;
        }
         if(p[i]>='0'&&p[i]<='9')
        {
            c3=1;
        }
if(p[i]=='!'||p[i]=='@'||p[i]=='#'||p[i]=='$'||p[i]=='%'||p[i]=='^'||p[i]=='&'||p[i]=='*'||p[i]=='('||p[i]==')'||p[i]=='-'||p[i]=='+')
        {
            c4=1;
        }
        i++;
    }
   // printf("%d %d %d %d\n",c1,c2,c3,c4);
    if(4-c1-c2-c3-c4<6-nn)
        return 6-nn;
    else
    return 4-c1-c2-c3-c4;
    // Return the minimum number of characters to make the password strong
}

int main() {
    int n; 
    scanf("%i", &n);
    char* password = (char *)malloc(512000 * sizeof(char));
    scanf("%s", password);
    int answer = minimumNumber(n, password);
    printf("%d\n", answer);
    return 0;
}