import core.bitop, std.algorithm, std.ascii, std.bigint, std.conv, std.math,
    std.functional, std.numeric, std.range, std.stdio, std.string, std.random,
    std.typecons, std.container, std.format, std.datetime;

// dfmt off
T lread(T = long)(){return readln.chomp.to!T();}
T[] lreads(T = long)(long n){return generate(()=>readln.chomp.to!T()).take(n).array();}
T[] aryread(T = long)(){return readln.split.to!(T[])();}
void scan(TList...)(ref TList Args){auto line = readln.split();
foreach (i, T; TList){T val = line[i].to!(T);Args[i] = val;}}
alias sread = () => readln.chomp();enum MOD = 10 ^^ 9 + 7;
alias PQueue(T, alias less = "a<b") = BinaryHeap!(Array!T, less);
// dfmt on

void main()
{
    long H, W;
    scan(H, W);
    auto S = new string[](H);
    foreach (i; 0 .. H)
        S[i] = sread();

    auto cost = new long[][](H, W);
    foreach (ref r; cost)
        r[] = long.max;

    auto visited = new bool[][](H, W);

    PQueue!(Tuple!(long, long, long), "b<a") PQ;
    PQ.insert(Tuple!(long, long, long)(0, 0, 0));
    while (!PQ.empty)
    {
        auto t = PQ.front();
        PQ.popFront();
        if (H <= t[1])
            continue;
        if (W <= t[2])
            continue;
        if (visited[t[1]][t[2]])
            continue;
        visited[t[1]][t[2]] = true;
        cost[t[1]][t[2]] = t[0];
        long b = S[t[1]][t[2]] == '#';
        PQ.insert(Tuple!(long, long, long)(t[0] + b, t[1] + 1, t[2]));
        PQ.insert(Tuple!(long, long, long)(t[0] + b, t[1], t[2] + 1));
    }
    writeln(cost[H - 1][W - 1] + (S[H - 1][W - 1] == '#'));
}
