#include<iostream>
#include<stack>

long Ackerman1(long m, long n)
{   
    if(m==0) return n+1;
    if(n==0) return Ackerman1(m-1,1);
    else     return Ackerman1(m-1,Ackerman1(m,n-1));
}
    
long Ackerman2(long m, long n)
{   
    std::stack<long> s;
    long operand1,operand2;
    s.push(m);    
    s.push(n);
    while(s.size()>1){
        operand2 = s.top();    s.pop();
        operand1 = s.top();    s.pop();
        if(operand1==0)
            s.push(operand2+1);
        else if(operand2==0){
            s.push(operand1-1);
            s.push(1);
        }
        else{
             s.push(operand1-1);
             s.push(operand1);
             s.push(operand2-1);
        }
    }
    return s.top();                     
}

int main()
{
     long m,n;
     std::cout << "intput the m and n!" << std::endl;
     std::cin >> m >> n;
     std::cout << "result of function1: " << Ackerman1(m,n) << std::endl;
     std::cout << "result of function2: " << Ackerman2(m,n) << std::endl;
     system("pause");
}