<script>

var m = [0, 0, 0, 0];
var all = 100000000;
var win = 0;

for (var i = 0; i < all; i++) {
    for (var j = 0; j < 4; j++) {
        m[j] = Math.round(Math.random(1));
    }
    var i1 = (m[0] == 1) ? 1 : 3;
    var i2 = (m[1] == 1) ? 0 : 2;
    if (m[i1] == m[i2]) {
        win++;
    }
}

document.write(win / all);

</script>