#include <math.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <assert.h>
#include <limits.h>
#include <stdbool.h>
int dig(int n,char * password){
    int i;
    for(i=0;i<n;i++){
        if(password[i]>='0' && password[i]<='9'){ return 1;}
    }
    return 0;
}

int lower(int n,char * password){
    int i;
    for(i=0;i<n;i++){
        if(password[i]>='a' && password[i]<='z'){ return 1;}
    }
    return 0;
}

int upper(int n,char * password){
    int i;
    for(i=0;i<n;i++){
        if(password[i]>='A' && password[i]<='Z'){ return 1;}
    }
    return 0;
}

int spe(int n,char * password){
    int i;
    for(i=0;i<n;i++){
        if(password[i]=='!'||password[i]=='@'||password[i]=='#'||password[i]=='$'||password[i]=='%'||password[i]=='^'||password[i]=='&'||password[i]=='*'||password[i]=='('||password[i]==')'||password[i]=='-'||password[i]=='+'){ return 1;}
    }
    return 0;
}

int minimumNumber(int n, char* password) {
    // Return the minimum number of characters to make the password strong
    int len=strlen(password);
    int digit,low,up,special;
    digit=dig(n,password);
    low=lower(n,password);
    up=upper(n,password);
    special=spe(n,password);
    int num_nil=0;
    if(digit==0){ num_nil++;}
    if(low==0){ num_nil++;}
    if(up==0){ num_nil++;}
    if(special==0){ num_nil++;}
    if(digit*up*low*special==1 && len>=6){
        return 0;
    }
    else if(digit*up*low*special==1 && len<6){
        return (6-len);
    }
    else{
        if(num_nil+len>=6){
            return num_nil;
        }
        else if(num_nil+len<6){
            return(6-len);
        }
    }
    return -1;
}

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;
}