RE求助

#include<bits/stdc++.h>
using namespace std;
long long a,b,c;
long long fa[25][25][25]={1};
long long f(long long a,long long b,long long c){
	if(fa[a][b][c]!=0){
		return fa[a][b][c];
	}else{
		if(a<=0||b<=0||c<=0){
			return 1;
		}else{
			if(a>20||b>20||c>20){
				fa[a][b][c]=f(20,20,20);
				return fa[a][b][c];
			}else{
				if(a<b&&b<c){
					fa[a][b][c]=f(a,b,c-1)+f(a,b-1,c-1)-f(a,b-1,c);
					return fa[a][b][c];
				}else{
					fa[a][b][c]=f(a-1,b,c)+f(a-1,b-1,c)+f(a-1,b,c-1)-f(a-1,b-1,c-1);
					return fa[a][b][c];
				}
			}
		}
	}
}
int main(){
	while(1==1){
		cin>>a>>b>>c;
		if(a==-1&&b==-1&&c==-1){
			return 0;
		}else{
			cout<<"w("<<a<<", "<<b<<", "<<c<<") = "<<f(a,b,c)<<endl;
		}
	}
	
	return 0;
}