10653_Bombs!NoTheyAreMines

#include <bits/stdc++.h>

using namespace std;

int R, C, a[1003][1003], ans[1003][1003], adj[1003];

void BFS(int x, int y) {
    queue <int> q;
    q.push(x); q.push(y);
    ans[x][y] = 0;

    int X[] = {-1, 0, 0, 1};
    int Y[] = {0, -1, 1, 0};
    while (!q.empty())
    {
        int Ux = q.front(); q.pop();
        int Uy = q.front(); q.pop();

        for (int i=0; i<4; ++i)
        {
            int Vx = Ux + X[i];
            int Vy = Uy + Y[i];

            if ((Vx>=0 && Vx<=R) && (Vy>=0 && Vy <= C) && !a[Vx][Vy])
                if (!ans[Vx][Vy])
                {
                    ans[Vx][Vy] = ans[Ux][Uy] + 1;
                    q.push(Vx); q.push(Vy);
                }
        }
    }
}

int main() {
    #ifndef ONLINE_JUDGE
        freopen("uva10653.inp", "r", stdin);
    #endif // ONLINE_JUDGE

    while (1)
    {
        scanf("%d%d", &R, &C);
        if (!R || !C) break;

        memset(a, 0, sizeof(a));
        memset(ans, 0, sizeof(ans));

        int r;
        scanf("%d", &r);
        for (int i=0; i<r; ++i)
        {
            int row, bomb;
            scanf("%d%d", &row, &bomb);
            for (int j=0; j<bomb; ++j)
            {
                int x;
                scanf("%d", &x);
                a[row][x] = 1;
            }
        }

        scanf("%d%d%d%d", &Sx, &Sy, &Tx, &Ty);
        BFS(Sx, Sy);
        printf("%d\n", ans[Tx][Ty]);
    }

    return 0;
}