#include<stdio.h>
int f(int *a, int n){
if(n<=0) return 0;
else if (*a%2==0) return *a+f(a+1, n-1);
else return *a-f(a+1, n-1);
}
int main(){
int a[]={12, 7, 13, 4, 11, 6};
printf("\n%d\n", f(a,6));
return 0;
}
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