#include <iostream>
#include <queue>
#include <cstring>
#define rangecheck(a,b) a<0 || a>=12 || b<0 || b>=6
using namespace std;
struct point {
	int r, c;
	char cnt;
};
queue<point> q, bamm_q;
char map[13][7];
bool visited[13][7];
bool flag;
int dr[] = { -1,0,1,0 };
int dc[] = { 0,1,0,-1 };
int cntt = 0;
int ans = 0;
void bfs(int r, int c) {
	point tmp = { r,c,0 };
	q.push(tmp);
	visited[r][c] = true;
	int nr, nc;
	while (!q.empty()) {
		r = q.front().r;
		c = q.front().c;
		bamm_q.push(q.front());
		q.pop();
		cntt++;
		//printf("%d %d %d %c\n", r, c, cntt, map[r][c]);
		for (int i = 0; i < 4; i++) {
			nr = r + dr[i];
			nc = c + dc[i];
			if (rangecheck(nr, nc)) continue;
			if (map[nr][nc] == map[r][c] && !visited[nr][nc]) {
				visited[nr][nc] = true;
				q.push({ nr,nc,0 });
			}
		}
	}
	//printf("\n");
}
void print() {
	for (int i = 0; i < 12; i++) {
		for (int j = 0; j < 6; j++) {
			printf("%c", map[i][j]);
		}
		printf("\n");
	}
	printf("\n");
}
void bamm() {
	for (int i = 0; i < 12; i++) {
		for (int j = 0; j < 6; j++) {
			if (map[i][j] != '.') {
				cntt = 0;
				bfs(i, j);
				if (cntt >= 4) {
					flag = true;
					while (!bamm_q.empty()) {
						map[bamm_q.front().r][bamm_q.front().c] = '.';
						bamm_q.pop();
					}
				}
				else {
					while (!bamm_q.empty()) {
						bamm_q.pop();
					}
				}
			}
		}
	}
}
void down() {
	for (int j = 0; j < 6; j++) {
		for (int i = 11; i >= 0; i--) {
			if (map[i][j] != '.') {
				q.push({ i,j,map[i][j] });
				map[i][j] = '.';
			}
		}
		int ii = 11;
		while (!q.empty()) {
			map[ii--][j] = q.front().cnt;
			q.pop();
		}
	}
}
void go() {
	flag = true;
	while (flag) {
		flag = false;
		bamm();
		down();
		memset(visited, false, sizeof(visited));
		//print();
		if (flag) ans++;
	}
}
int main() {
	for (int i = 0; i < 12; i++) {
		for (int j = 0; j < 6; j++) {
			scanf(" %1c", &map[i][j]);
		}
	}
	go();
	printf("%d\n", ans);
	return 0;
}