N = int(input())
S = input().strip()

parok = []
for i in range(1, N + 1):
    for j in range(i + 1, N + 1):
        parok.append((i, j))

betu_par = dict(zip("ABCDEFGHIJKLMNOPQRSTUVWXYZ", parok))

labda = 1

for betu in S:
    elso, masodik = betu_par[betu]
    if labda == elso:
        labda = masodik
    elif labda == masodik:
        labda = elso

print(labda)