#include<cstdio>
#include<cstring>
char s[55];

int main(){
    scanf("%s",s+1);
    int n = strlen(s+1);
    int mod2 = 0, mod4 = 0;
    for(int i = 1; i <= n; i++){
        int u = s[i]-'0';
        mod2 = (mod2*10+u)%2;
        mod4 = (mod4*10+u)%4;
    }
    if(n==1 && s[1]=='1') printf("1\n");
    else if(mod2!=0 || mod4==0) printf("1\n");
    else printf("-1\n"); 
    return 0;
}