救救救！

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

哪里有问题啊啊啊