#include <cstdio>
#include <cctype>
#include <vector>
#include <algorithm>
using namespace std;
const int maxn = 1e5 + 100;
inline int read(){
int x = 0;char c = getchar();
while(!isdigit(c))c = getchar();
while(isdigit(c))x = x * 10 + c - '0',c = getchar();
return x;
}
int n,m,va[maxn],vb[maxn];
inline bool check(int limit){
int pos = 1;
for(int i = 1;i <= m;i++){
while(pos <= n && abs(va[pos] - vb[i]) > limit)pos++;
if(pos == n + 1)return false;
pos++;
}
return true;
}
int main(){
n = read(),m = read();
for(int i = 1;i <= n;i++)va[i] = read();
for(int i = 1;i <= m;i++)vb[i] = read();
if(n < m)swap(n,m),swap(va,vb);
sort(va + 1,va + 1 + n);
sort(vb + 1,vb + 1 + m);
int l = 0,r = min(abs(va[1] - vb[m]),abs(vb[1] - va[n])),ans = -1;
while(l <= r){
int mid = (l + r) >> 1;
if(check(mid))ans = mid,r = mid - 1;
else l = mid + 1;
}
printf("%d\n",ans);
return 0;
}
