Interesen Broj - SP Lab 3

#include <stdio.h>
int main (){
    int n, brcif=0, dn, dekadenbr=1, cifra, obratensum=0;
    scanf("%d", &n);
    if(n<=9){
        printf("Nevaliden");
    }
    else{
        dn=n;
        for(;dn;){
            dn/=10;
            brcif++;
            dekadenbr*=10;
        }
        printf("%d\n", brcif);
        printf("%d\n", dekadenbr);
        dn=n;
        for(;dn;){
            obratensum+=1000*cifra=dn%10;
            dekadenbr/=10;
            dekadenbr 100;
        }
        if(obratensum%brcif==0){
            printf("Interesno");
        }
    }
    return 0;
}