exponencial

# include <stdio.h>
# include <stdlib.h>
int expo (int x, int n );
int main (void)
{
int x=2;
int n;
scanf("%d", &n);
printf("%d", expo(x,n));
system ("pause");
return 0;
}

int expo (int x, int n )
{
if (n==0)
return 1;
if(n%2==0){
int res= expo (x, n/2);
res=res*res;
return res%1000;
}
int res= expo (x, n/2);
res=res*res;
res=res*x;
return res%1000;
}