题解 | #矩阵计算#

n,m = map(int, input().split())
k = []
num = 0
for i in range(n):
    k.append(input().split())
for x in range(n):
    for y in range(m):
        if int(k[x][y]) > 0:
            num += int(k[x][y])
        else:
            continue
print(num)