function countbackgrounds() {
var book = SpreadsheetApp.getActiveSpreadsheet();
var sheet = book.getActiveSheet();
var range_input = sheet.getRange("B3:B4");
var range_output = sheet.getRange("B6");
var cell_colors = range_input.getBackgroundColors();
var color = "#58FA58";
var count = 0;
for(var r = 0; r < cell_colors.length; r++) {
for(var c = 0; c < cell_colors[0].length; c++) {
if(cell_colors[r][c] == color) {
count = count + 1;
}
}
}
range_output.setValue(count);
}