#!/usr/bin/python3

slope = []
with open("input") as fh:
    for ln in fh:
        row = []
        for c in ln:
            if c == "#":
                row.append(True)
            elif c == ".":
                row.append(False)
            elif c == "\n":
                pass
            else:
                raise RuntimeError("impossible")
        slope.append(row)
xmod = len(slope[0])
x = 0
y = 0
trees = 0
while y < len(slope):
    trees += slope[y][x % xmod]
    x += 3
    y += 1
print(trees)