import std.stdio, std.string, std.conv;
import std.range, std.algorithm, std.array, std.typecons, std.container;
import std.math, std.numeric, core.bitop;

enum inf = 1_001_001_001;
enum inf6 = 1_001_001_001_001_001_001L;
enum mod = 1_000_000_007L;



void main() {
    int H, W;
    scan(H, W);
    auto b = new bool[][](H, W);
    foreach (i ; 0 .. H) {
        b[i] = readln.chomp.map!(c => c == '.').array;
    }

    debug {
        writeln(b);
    }

    auto u = new int[][](H, W);
    auto d = new int[][](H, W);
    auto r = new int[][](H, W);
    auto l = new int[][](H, W);

    foreach (i ; 1 .. H) {
        foreach (j ; 0 .. W) {
            if (b[i - 1][j]) u[i][j] += u[i - 1][j] + 1;
        }
    }

    foreach_reverse (i ; 0 .. H - 1) {
        foreach (j ; 0 .. W) {
            if (b[i + 1][j]) d[i][j] += d[i + 1][j] + 1;
        }
    }

    foreach (j ; 1 .. W) {
        foreach (i ; 0 .. H) {
            if (b[i][j - 1]) l[i][j] += l[i][j - 1] + 1;
        }
    }

    foreach_reverse (j ; 0 .. W - 1) {
        foreach (i ; 0 .. H) {
            if (b[i][j + 1]) r[i][j] += r[i][j + 1] + 1;
        }
    }

    int ans;

    foreach (i ; 0 .. H) {
        foreach (j ; 0 .. W) {
            if (!b[i][j]) continue;
            chmax(ans, u[i][j] + d[i][j] + l[i][j] + r[i][j] + 1);
        }
    }

    writeln(ans);
}














void scan(T...)(ref T args) {
    import std.stdio : readln;
    import std.algorithm : splitter;
    import std.conv : to;
    import std.range.primitives;

    auto line = readln().splitter();
    foreach (ref arg; args) {
        arg = line.front.to!(typeof(arg));
        line.popFront();
    }
    assert(line.empty);
}

void fillAll(R, T)(ref R arr, T value) {
    static if (is(typeof(arr[] = value))) {
        arr[] = value;
    }
    else {
        foreach (ref e; arr) {
            fillAll(e, value);
        }
    }
}

bool chmin(T, U...)(ref T x, U args) {
    bool isChanged;

    foreach (arg; args) {
        if (x > arg) {
            x = arg;
            isChanged = true;
        }
    }

    return isChanged;
}

bool chmax(T, U...)(ref T x, U args) {
    bool isChanged;

    foreach (arg; args) {
        if (x < arg) {
            x = arg;
            isChanged = true;
        }
    }

    return isChanged;
}
