for example :
Here a is three(3).
 
calling  fun(3) in main function.
 FUN(3) {
    calling fun(2) {
	calling fun(1)  {
  	    calling fun(0) {
		N>0 found.
            }
	    printed 0				
            calling second fun(-1) {
		N>0 found. 
            }
        }
	printed 1					
        calling second fun(0) {
       	    N>0 found.
        }
    }
     printed 2		
     calling second fun(1) {
	 calling fun(0) { 
	     N>0 found.
         } 
	 printed 0		
         calling second fun(-1) {
 	     N>0 found.
         } 
     }
 }