1029. Rabbit

#include <iostream>

using namespace std;

string stringAdd(string a, string b) {
	while(a.length() < b.length()) {
		a = "0" + a;
	}
	while(b.length() < a.length()) {
		b = "0" + b;
	}
	string tmp = "";
	int carry = 0;
	for(int i = a.length() - 1; i >= 0; i--) {
		int bitsum = static_cast<int>(a[i] - '0') + static_cast<int>(b[i] - '0') + carry;
		carry = bitsum / 10;
		bitsum %= 10;
		tmp = static_cast<char>(bitsum + '0') + tmp;
	}
	if(carry) {
	    tmp = static_cast<char>(carry + '0') + tmp;
	}
	return tmp;
}

int main() {
	int m, d;
	while(cin >> m >> d) {
		if(m == 0 && d == 0) {
			break;
		}
		string child[m];
		for(int i = 0; i < m; i++) {
			child[i] = "0";
		}
		string adult = "1";
		for(int i = 1; i <= d; i++) {
			adult = stringAdd(adult, child[m-1]);
			for(int j = m - 1; j > 0; j--) {
				child[j] = child[j-1];
			}
			child[0] = adult;
		}
		string total = adult;
		for(int i = 0; i < m; i++) {
			total = stringAdd(total, child[i]);
		}
		cout << total << endl;
	}
	return 0;
}