w=int(input())
m=str(input())
l=len(m)
i=1
for i in range (l):
    n=ord(m[i])
    if n+w>122:
        n=n-25
        if n<97:
            n=194-n
    else:
        n=n+w
    mi=chr(n)
    print(mi,end='')
    i+=1