How can we find the output of recursion program in quicker way in c?

How can we find the
output of recursion program in quicker way in c programming language


(1)What will be output of following c recursion program?




#include
int main(){

    int x,num=4;

    x=call(num);

    printf("%d",x);

    return 0;



}

int call(int num){

    static int x=1,y;

    if(num>0){

         x=x*num;

         y=call(num-1)+call(num-2);

    }

    return x;