Problems

# Count sources

# Count sources

The directed graph is given with the adjacency list. The vertex of directed graph is called a source if no edge comes into it. Count the number of sources in the graph.

## Input data

First line contains the number of vertices n (1 ≤ n ≤ 100). The next i-th line contains the number of edges adjacent to the i-th vertex, and the vertex numbers where these edges go in increasing order.

## Output data

Print the number of sources in the graph.

#### Example

Graph contains 1 source - the vertex number 4.

## Examples

Input example #1

5 1 3 2 1 3 1 5 2 1 2 2 1 2

Output example #1

1