import sys

sys.setrecursionlimit(10**6)
int1 = lambda x: int(x)-1
p2D = lambda x: print(*x, sep="\n")
def II(): return int(sys.stdin.buffer.readline())
def FI(): return float(sys.stdin.buffer.readline())
def MI(): return map(int, sys.stdin.buffer.readline().split())
def MF(): return map(float, sys.stdin.buffer.readline().split())
def MI1(): return map(int1, sys.stdin.buffer.readline().split())
def LI(): return list(map(int, sys.stdin.buffer.readline().split()))
def LI1(): return list(map(int1, sys.stdin.buffer.readline().split()))
def LLI(rows_number): return [LI() for _ in range(rows_number)]
def LLI1(rows_number): return [LI1() for _ in range(rows_number)]
def BI(): return sys.stdin.buffer.readline().rstrip()
def SI(): return sys.stdin.buffer.readline().rstrip().decode()
dij = [(0, 1), (-1, 0), (0, -1), (1, 0)]
inf = 10**16
md = 998244353
# md = 10**9+7

n=II()
ps=""
pii=[]
ans=0
for i in range(n):
    s=BI()
    ii=[i]*len(s)
    for j,(c1,c2) in enumerate(zip(s,ps)):
        if c1!=c2:break
        ii[j]=pii[j]
    ans+=sum((i-pi+1)*(i-pi+2)//2 for pi in ii)
    # print(ans,ii)
    ps=s
    pii=ii

print(ans)