# Write a Pandas program to Combine two DataFrame objects by filling null values in one DataFrame with non-null values from other DataFrame.  
import pandas as pd
df1 = pd.DataFrame({'A': [None, 0, None], 'B': [3, 4, 5]})
df2 = pd.DataFrame({'A': [1, 1, 3], 'B': [3, None, 3]})
df1.combine_first(df2)
print("Original DataFrames:")
print(df1)
print("--------------------")
print(df2)
print("\nMerge two dataframes with different columns:")
result = df1.combine_first(df2)
print(result)
