c = input()
x = input()
x = x.split(' ')
y = []
if len(x)==1:
print(x[0], end = '')
print(3, end = '')
elif len(x)==2:
print(x[0], end = '')
print(3, end = '')
else:
print(x[0], end = '')
for i in range(len(x[1])-1):
if x[1][i]<=x[1][i+1] and x[1][i]!=x[2][i]:
y.append(x[1][i])
else:
continue
print(''.join(y), end = '')
print(x[2])
1566B - MIN-MEX Cut | 678C - Joty and Chocolate |
1352E - Special Elements | 1520E - Arranging The Sheep |
1157E - Minimum Array | 1661D - Progressions Covering |
262A - Roma and Lucky Numbers | 1634B - Fortune Telling |
1358A - Park Lighting | 253C - Text Editor |
365B - The Fibonacci Segment | 75A - Life Without Zeros |
1519A - Red and Blue Beans | 466A - Cheap Travel |
659E - New Reform | 1385B - Restore the Permutation by Merger |
706A - Beru-taxi | 686A - Free Ice Cream |
1358D - The Best Vacation | 1620B - Triangles on a Rectangle |
999C - Alphabetic Removals | 1634C - OKEA |
1368C - Even Picture | 1505F - Math |
1473A - Replacing Elements | 959A - Mahmoud and Ehab and the even-odd game |
78B - Easter Eggs | 1455B - Jumps |
1225C - p-binary | 1525D - Armchairs |