UVa 1594 Ducci

#include <iostream>
#include <cmath>
using namespace std;
int Lu[5], flag;
int main(){
for (int i = 1; i <= 4; i++){
scanf("%d", &Lu[i]);
}
int i;
for (i = 1; i <= 1000; i++){
flag = 0;
int m = Lu[1];
for (int i = 1; i <= 3; i++)
Lu[i] = abs(Lu[i + 1] - Lu[i]);
Lu[4] = abs(m - Lu[4]);
for (int i = 1; i <= 4; i++)
if (Lu[i] == 0)
flag++;
if (flag == 4){
printf("Zero\n");
break;
}
}
if (i == 1000)
printf("Loop\n");
return 0;
}