1 #include <cmath>
 2 #include <cstdio>
 3 #include <iostream>
 4 #include <algorithm>
 5 #define ll long long
 6 using namespace std;
 7 double a;
 8 double dis(ll x,ll y) { return sqrt(x*x+y*y); }
 9 ll cross(ll x1,ll y1,ll x2,ll y2) { return x1*y2-x2*y1; }
10 double getcos(ll x1,ll y1,ll x2,ll y2) { return (double)(x1*x2+y1*y2)/(dis(x1,y1)*dis(x2,y2)); }
11 int main()
12 {
13     freopen("math.in","r",stdin),freopen("math.out","w",stdout);
14     ll x1,y1,x2,y2,k;
15     while (scanf("%lld%lld%lld%lld",&x1,&y1,&x2,&y2)!=EOF)
16     {
17         if (cross(x1,y1,x2,y2)==0) { printf("0\n"); continue; }
18         while (1)
19         {
20             if (dis(x1,y1)>dis(x2,y2)) swap(x1,x2),swap(y1,y2);
21             a=getcos(x1,y1,x2,y2);
22             if (a<0) { x1=-x1,y1=-y1;continue; }
23             if (a<0.5) break;
24             k=dis(x2,y2)*a/dis(x1,y1)+0.5,x2-=k*x1,y2-=k*y1;
25         }
26         printf("%lld\n",min(x1*x1+y1*y1,x2*x2+y2*y2));
27     }
28 }