TLE求看

#include<cstdio>
#define int long long

int w(int a,int b,int c){
	if(a<=0||b<=0||c<=0)
		return 1;
	if(a>20||b>20||c>20)
		return w(20,20,20);
	return w(a-1,b,c)+w(a-1,b-1,c)+w(a-1,b,c-1)-w(a-1,b-1,c-1);
}
signed main(){
	int i,a=0,b=0,c=0;
	scanf("%d%d%d",&a,&b,&c);
	for(i=0;a!=-1||b!=-1||c!=-1;i++){
		printf("w(%d, %d, %d) = %d\n",a,b,c,w(a,b,c));
		scanf("%d%d%d",&a,&b,&c);
	}
	return 0;
}