public int climbStairs(int n) {
	        if(n==1) return 1;
	        else if(n==2) return 2;
	        else{
	            int[] count = new int[n];
	            count[0]=1;
	            count[1]=2;
	            for(int i=2; i<n; i++){
	                int a = count[i-1];
	                int b = count[i-2];
	                int c = a+b;
	                count[i] = c;
	            }
	            return count[n-1];
	        }
	    }