UVa-674-Coin Change

// 674 - Coin Change
#include <iostream>
#include <cstring>
#define MAXN 7500
using namespace std;

int coin[5] = {1, 5, 10, 25, 50};
int a[MAXN][5];
int m;

int dp(int m, int n)
{
if(a[m]
!= -1)
return a[m]
;
a[m]
= 0;
for(int i = n; i < 5; i++)
if(m >= coin[i])
a[m]
+= dp(m-coin[i], i);
return a[m]
;
}

int main(void)
{
memset(a, -1, sizeof(a));
for(int i = 0; i < 5; i++)
a[0][i] = 1;
while(cin >> m)
cout << dp(m, 0) << endl;
return 0;
}