C :

#include <stdio.h>

int main() {
	int n, a;
	int i, c, m;
	int b[20];
	scanf("%d", &n);
	c = n;
	i = 0;
	while (c > 0) {
		b[i] = c % 10;
		i++;
		c = c / 10;
	}



	for (m = i - 1; m >= 0; m--) {

		switch (b[m]) {
			case 0:
				printf("zero");
				break;
			case 1:
				printf("one");
				break;
			case 2:
				printf("two");
				break;
			case 3:
				printf("three");
				break;
			case 4:
				printf("four");
				break;
			case 5:
				printf("five");
				break;
			case 6:
				printf("six");
				break;
			case 7:
				printf("seven");
				break;
			case 8:
				printf("eight");
				break;
			case 9:
				printf("nine");
				break;
		}
		if (m > 0) {

			printf("-");
		}
	}


	return 0;
}

C++ :

#include <bits/stdc++.h>
using namespace std;
int main() {
	string s;
	cin >> s;
	int len = s.size();
	for (int i = 0; i < len; i++) {
		if (s[i] - '0' == 0)
			cout << "zero";
		else if (s[i] - '0' == 1)
			cout << "one";
		else if (s[i] - '0' == 2)
			cout << "two";
		else if (s[i] - '0' == 3)
			cout << "three";
		else if (s[i] - '0' == 4)
			cout << "four";
		else if (s[i] - '0' == 5)
			cout << "five";
		else if (s[i] - '0' == 6)
			cout << "six";
		else if (s[i] - '0' == 7)
			cout << "seven";
		else if (s[i] - '0' == 8)
			cout << "eight";
		else if (s[i] - '0' == 9)
			cout << "nine";
		if (i != len - 1)
			cout << "-";
	}
	return 0;
}