n, m = map(int, input().split())
s = {input() for _ in range(n)}; t = s.pop()
l = []; r = []; lrl = set(); lrr = set()
flag = True; ans = 0
for v in s:
    a = b = False
    if v[1:] == t[:-1]: a = True
    if v[:-1] == t[1:]: b = True
    if a and b: lrl.add(v[0]); lrr.add(v[-1])
    elif a: l.append(v[0])
    elif b: r.append(v[-1])
    else: flag = False
if flag and len(l)+len(r) <= 1:
    if l:
        if not lrl or len(lrl) == 1 and lrl.pop() == l[0]: ans = 1
    elif r:
        if not lrr or len(lrr) == 1 and lrr.pop() == r[0]: ans = 1
    else:
        if not lrl: ans = 52
        else:
            if len(lrl) == 1: ans += 1
            if len(lrr) == 1: ans += 1
print(ans)