public class Main {
	public static void main(String[] args) {
		System.out.println(decode("a2bc10d1"));
	}
	public static String decode(String str){
		
		if (str==null||str.length()==0) {
			return null;
		}
		
		String[] strstr = str.split("\\d+");
		String[] strnum = str.split("[a-zA-Z]+");
		
		StringBuilder stringBuilder = new StringBuilder();
		
		int i=0;//统计strstr
		int j=0;//统计strnum
		while (i<strstr.length&&j<strnum.length) {
			if (strnum[j]!=null&&!strnum[j].equals("")) {
				int num = Integer.parseInt(strnum[j]);
				for (int k = 0; k < num; k++) {
					stringBuilder.append(strstr[i]);
				}
				i++;
			}
			j++;
			
		}
		return new String(stringBuilder);
	}
}