from itertools import chain
#runtime error 80/100

rows, cols = [int(n) for n in input().split(' ')]

matrix = [[x for x in input().split(' ')] for u in range(rows)]

squares = []

for i in range(len(matrix)-1):
    row = matrix[i]
    for j in range(len(row)-1):
        square = [
            [matrix[i][j]], [matrix[i][j+1]],
            [matrix[i+1][j]], [matrix[i+1][j+1]],
        ]
        squares.append(square)

overall_count = 0
for item in squares:
    current_list = []
    for char in item:
        current_list.append(char[0])
    if len(set(current_list)) == 1:
        overall_count += 1

print(overall_count)