#include <cstdio>
#include <cstdlib>
#include <algorithm>
#include <cmath>
#include <vector>
using namespace std;
const double eps = 1e-8;
bool db_eq(const double& a, const double& b){return fabs(a-b) <= eps;}
bool db_ne(const double& a, const double& b){return fabs(a-b) > eps;}
bool db_bg(const double& a, const double& b){return a-b >= -eps;}
bool db_sg(const double& a, const double& b){return a-b <= eps;}
bool db_s(const double& a, const double& b){return a-b <= -eps;}
bool db_b(const double& a, const double& b){return a-b > eps;}
bool db_z(const double& a){return fabs(a) < eps;}
bool db_nz(const double& a){return fabs(a) >= eps;}
bool db_pos(const double& a){return a>= eps;}
bool db_neg(const double& a){return a<=-eps;}
struct pt{ double x, y; pt(double _x = 0, double _y = 0): x(_x), y(_y){return;}};
pt operator+(const pt& a, const pt& b){return pt(a.x+b.x, a.y+b.y);}
pt operator-(const pt& a, const pt& b){return pt(a.x-b.x, a.y-b.y);}
double operator^(const pt& a, const pt& b){return a.x*b.y - a.y*b.x;}
pt operator~(const pt& a){return pt(a.y, -a.x);}
bool operator==(const pt& a, const pt& b){return db_eq(a.x,b.x) and db_eq(a.y,b.y);}
struct line{
double a, b, c;
line(pt m, pt p){
a = m.y; b = -m.x;
c = -a*p.x - b*p.y;
return;
}
double len()const{return sqrt(a*a + b*b);}
pt m()const{return pt(a, -b);}
};
struct ch_cpx{bool operator()(const pt& a, const pt& b){return db_ne(a.x, b.x) ? db_s(a.x, b.x) : db_s(a.y, b.y);}};
vector<pt> make_ch(vector<pt>& inp){
sort(inp.begin(), inp.end(), ch_cpx());
auto it = unique(inp.begin(), inp.end());
inp.resize(distance(inp.begin(), it));
int inpsz = inp.size();
vector<pt> bt(inpsz), tp(inpsz);
int btsz = 0, tpsz = 0;
for(int lx = 0;lx < inpsz;lx++){
while(btsz > 1 and db_pos((bt[btsz-2] - bt[btsz-1])^(inp[lx] - bt[btsz-1])))
btsz--;
bt[btsz++] = inp[lx];
}
for(int lx = inpsz-1;lx >= 0;lx--){
while(tpsz > 1 and db_pos((tp[tpsz-2] - tp[tpsz-1])^(inp[lx] - tp[tpsz-1])))
tpsz--;
tp[tpsz++] = inp[lx];
}
vector<pt> ret;
for(int lx = 0;lx < btsz;lx++) ret.push_back(bt[lx]);
for(int lx = 1;lx < tpsz-1;lx++) ret.push_back(tp[lx]);
return ret;
}
int eval(const vector<pt>& ch, const line& l){
int acnt = 0, bcnt = 0;
for(int lx = 0;lx < ch.size();lx++){
double val = l.a*ch[lx].x + l.b*ch[lx].y + l.c;
if(db_pos(val)) acnt++;
if(db_neg(val)) bcnt++;
}
if(acnt and bcnt) return 2; //err
if(acnt) return 1;
if(bcnt) return -1;
return 0;
}
double cal(const vector<pt>& cha, const vector<pt>& chb, line la, line lb){
int val_aa = eval(cha, la);
int val_ab = eval(cha, lb);
int val_ba = eval(chb, la);
int val_bb = eval(chb, lb);
if(val_aa == 2 or val_ab == 2 or val_ba == 2 or val_bb == 2) return 0;
if(val_aa == val_ba and val_aa != 0) return 0;
if(val_ab == val_bb and val_ab != 0) return 0;
if(db_nz(la.m()^lb.m())) return 0;
double k = 0;
if(db_nz(la.a)) k = lb.a/la.a;
if(db_nz(la.b)) k = lb.b/la.b;
return fabs(la.c*k-lb.c)/la.len();
}
int main(){
int m, n;
for(;;){
scanf("%d %d", &m, &n);
if(n == 0 and m == 0) break;
vector<pt> ap(m), bp(n);
for(int lx = 0;lx < m;lx++) scanf("%lf %lf", &ap[lx].x, &ap[lx].y);
for(int lx = 0;lx < n;lx++) scanf("%lf %lf", &bp[lx].x, &bp[lx].y);
ap = make_ch(ap);
bp = make_ch(bp);
double dis = 0;
int sza = ap.size(), szb = bp.size();
for(int lx = 0;lx < sza;lx++){
for(int ly = 0;ly < szb;ly++){
line la = line(~(ap[lx]-bp[ly]),ap[lx]);
line lb = line(~(ap[lx]-bp[ly]),bp[ly]);
dis = max(dis, cal(ap, bp, la, lb));
}
}
// p2l
for(int lx = 0;lx < sza and sza > 1;lx++){
for(int ly = 0;ly < szb;ly++){
line la = line(ap[lx]-ap[(lx+1)%sza], ap[lx]);
line lb = line(ap[lx]-ap[(lx+1)%sza], bp[ly]);
dis = max(dis, cal(ap, bp, la, lb));
}
}
// l2p
for(int lx = 0;lx < sza;lx++){
for(int ly = 0;ly < szb and szb > 1;ly++){
line la = line(bp[ly]-bp[(ly+1)%szb], ap[lx]);
line lb = line(bp[ly]-bp[(ly+1)%szb], bp[ly]);
dis = max(dis, cal(ap, bp, la, lb));
}
}
//l2l
for(int lx = 0;lx < sza and sza > 1;lx++){
for(int ly = 0;ly < szb and szb > 1;ly++){
line la = line(ap[lx]-ap[(lx+1)%sza], ap[lx]);
line lb = line(bp[ly]-bp[(ly+1)%szb], bp[ly]);
dis = max(dis, cal(ap, bp, la, lb));
}
}
if(db_z(dis)) printf("IMPOSSIBLE\n");
else printf("%.3f\n", dis);
}
return 0;
}
