import java.util.*;

public class Main {
public static <T> Map<T, Integer> mergeMaps(
final Map<T, Integer>... maps) {
final Map<T, Integer> merged = new HashMap<T, Integer>();
for (final Map<T, Integer> map : maps) {
for (final Map.Entry<T, Integer> entry : map.entrySet()) {
if (entry.getValue() != null && entry.getValue() != 0) {
final Integer curValue = merged.get(entry.getKey());
merged.put(entry.getKey(),
curValue == null ? entry.getValue() : curValue
+ entry.getValue());
}
}
}
return merged;
}
}