ander franz - gg ok

#include <bits/stdc++.h>

using namespace std;

#define min(a, b) ((a)<(b)?(a):(b))
#define MAX 9999.99999

struct Point { double x, y; };
Point p[10001];

double dist(Point p1, Point p2) {
    return hypot(p1.x - p2.x, p1.y - p2.y);
}

int compare(const void *a, const void *b){
    Point *sp1 = (Point *)a;
    Point *sp2 = (Point *)b;
    if (sp1->x > sp2->x) return 1;
    else if (sp1->x < sp2->x) return -1;
    else if (sp1->y > sp2->y) return 1;
    return -1;
}

double closest(long a, long b) {
    double d1, d2, d, xp;
    long i, j, k;

    if(a == b)
        return MAX + 1.0;
    else if(b - a == 1)
        return dist(p[b], p[a]);
    else {
        int mid = (a + b) >> 1;

        d1 = closest(a, mid);
        d2 = closest(mid + 1, b);

        d = min(d1, d2);

        xp = p[mid].x;

        j = mid;
        do {
            k = mid + 1;
            while(xp - p[k].x < d && k <= b) {
                d1 = dist(p[k], p[j]);
                d = min(d, d1);
                k++;
            }
            j--;
        } while (xp - p[j].x < d && j >= a);

    return d;
    }
}

int main() {
    int t;
    double d;
    while (scanf("%d", &t), t != 0) {
        for (int i = 0; i < t; i++)
            scanf("%lf%lf", &p[i].x, &p[i].y);

        qsort(p, t, sizeof(p[0]), compare);

        d = closest(0, t - 1);
        (d > MAX) ? puts("INFINITY") : printf("%.4lf\n", d);
    }
}