#pragma GCC optimize("Ofast")
#pragma GCC target("avx2")

char*mmap();
#define RD(v) int v=0;{int c;while(c=*rp++-48,c>=0)v=v*10+c;}

char a[1000001];

main(){
	char*rp=mmap(0l,800l<<10,1,2,0,0ll);
	while(*rp++!=10);
	do{
		RD(x);
		a[x]=1;
	}while(*rp);
	int z=1<<20,y=-z;
	for(int i=0;i<1000001;++i){
		if(a[i]){
			if(z>i-y){
				z=i-y;
			}
			y=i;
		}
	}
	z&=(1<<20)-1;
	char wbuf[16],*wp=wbuf+16;
	while(*--wp=z%10+48,z/=10);
	write(1,wp,wbuf+16-wp);
	_exit(0);
}