#include <stdio.h>

int ISBN13(char* c);

int main(void)
{
    char number[10000];
    char *pointer=number;

    printf("Please insert International Standard Book Number\n");
    pointer = fgets(number,10000,stdin); //Overflow zbog prevelikog broja znakova je tu nemoguće izbjeći jer se ne smije koristiti dinamička alokacija memorije
    printf("%d",ISBN13(pointer));
    return 0;
}

int ISBN13(char* number){
    char* temp =number;
    int length=0, digitsNumber=0, hyphensNumber=0;
    int prefixSize=0, regGroupSize=0, regElSize=0, pubElSize=0, checkDigitSize=0;
    char prefix[10000],regGroup[10000],regEl[10000],pubEl[10000],checkDigit[10000];
    for(;*temp!='\0' && *temp!=10 ;temp++){
        length++;
        if(*temp==45){
            hyphensNumber++;
        }
        else if(*temp>=48 && *temp<=57){
            digitsNumber++;

            if(hyphensNumber<1){
                prefix[prefixSize]=*temp;
                prefix[++prefixSize]='\0';
            }
            if(hyphensNumber==1){
                regGroup[regGroupSize]=*temp;
                regGroup[++regGroupSize]='\0';
            }
            if(hyphensNumber==2){
                regEl[regElSize]=*temp;
                regEl[++regElSize]='\0';
            }
            if(hyphensNumber==3){
                pubEl[pubElSize]=*temp;
                pubEl[++pubElSize]='\0';
            }
            if(hyphensNumber==4){
                checkDigit[checkDigitSize]=*temp;
                checkDigit[++checkDigitSize]='\0';
            }
        }
        else{
                return -1;
            }

    }

    if(digitsNumber!=13){
        return -2;
    }
    if(hyphensNumber!=4){
        return -3;
    }
    if(prefixSize!=3){
        return -4;
    }
    else{
        if(prefix[0]!='9' || prefix[1]!='7' || (prefix[2]!='8' && prefix[2]!='9')){
            return -4;
        }
    }
    if(regGroupSize<1 || regGroupSize>5){
            return -5;
    }
    if(regElSize>7){
        return -6;
    }
    if(pubElSize>6){
        return -7;
    }
    if((regGroupSize+regElSize+pubElSize)!=9){
        return -8;
    }
    if(checkDigitSize!=1){
        return -9;
    }
    else{
        int sum = 0;
        int multiplier=1;
        for(int i=0;i<prefixSize;i++){
            sum = sum +(prefix[i]-48)*multiplier;
            if(multiplier==1){
                multiplier=3;
            }
            else{
                multiplier=1;
            }
        }
        for(int i=0;i<regGroupSize;i++){
            sum = sum +(regGroup[i]-48)*multiplier;
            if(multiplier==1){
                multiplier=3;
            }
            else{
                multiplier=1;
            }
        }
        for(int i=0;i<regElSize;i++){
            sum = sum +(regEl[i]-48)*multiplier;
            if(multiplier==1){
                multiplier=3;
            }
            else{
                multiplier=1;
            }
        }
        for(int i=0;i<pubElSize;i++){
            sum = sum +(pubEl[i]-48)*multiplier;
            if(multiplier==1){
                multiplier=3;
            }
            else{
                multiplier=1;
            }
        }
        int mod = sum % 10;
        int digit = 10-mod;
        if(digit!= checkDigit[0]-48){
            return -9;
        }
    }
return 0;
}