#include <bits/stdc++.h>
using namespace std;
#define mems(x, y) memset(x, y, sizeof(x))
int n, m = 0, dis[65540][17];
bool bk[65540][17];
char c[1010];
struct Node{
	int x, len;
	bool operator <(const Node u) const{ return dis[x][len] > dis[u.x][len]; }
}a[1010];
Node mrg(Node u, Node v){
	if(u.len > v.len) return mrg(v, u);
	if(u.x != (v.x & (1 << u.len) - 1)) return {-1, 0};
	return {v.x >> u.len, v.len - u.len};
}
priority_queue <Node> q;
int main()
{
	int i, j;
	Node u, v;
	scanf("%d", &n);
	mems(c, '\0'); mems(dis, 0x3f3f3f3f); mems(bk, false);
	for(i = 1; i <= n; i++){
		scanf("%s", c);
		for(j = 0, a[i].x = 0; c[j] >> 1 == 24; j++){
			if(c[j] ^ '0') a[i].x |= 1 << j;
			c[j] = '\0';
		}
		a[i].len = j;
	}
	for(i = 1; i <= n; i++){
		for(j = i + 1; j <= n; j++){
			if(i != j){
				u = mrg(a[i], a[j]);
				if(u.x >= 0){ dis[u.x][u.len] = min(a[i].len, a[j].len); q.push(u); }
			}
		}
	}
	while(q.size() > 0){
		u = q.top(); q.pop();
		if(u.len == 0){ printf("%d", dis[u.x][u.len]); return 0; }
		if(bk[u.x][u.len]) continue;
		bk[u.x][u.len] = true;
		for(i = 1; i <= n; i++){
			v = mrg(u, a[i]);
			if(v.x >= 0){ dis[v.x][v.len] = min(dis[v.x][v.len], dis[u.x][u.len] + min(a[i].len, u.len)); q.push(v); }
		}
	}
	printf("0");
	return 0;
}