Checking for water flow through a block

waterflow.py

def physics(data):
    block = [[int(i) for i in row.split(',')] for row in data.split(';')]
    width = len(block[0])
    height = len(block)
    
    water = block[0].index(1)
    for row in range(1,height):
        for possible in (-1,0,1):
            if water+possible in range(width) and block[row][water+possible]:
                water += possible
                break
        else:
            print("blocked at level", row)
            return "No"
    return "Yes"
    
#string = input("Enter: ")
string = "1,0,0,0,0;0,1,0,0,0;0,1,0,0,0;0,0,1,0,0;0,0,0,1,0"
print(physics(string))
string = "1,0,0,0,0;0,0,1,0,0;0,1,0,0,0;0,0,1,0,0;0,0,0,1,0"
print(physics(string))
# Output:
# Yes
# blocked at level 1
# No