#include <stdio.h>
int main(void) {
int a[30];
int i;
a[0]=2;
a[1]= -1;
for(i=2;i<30;i++){
a[i]= -a[i-1]+a[i-2]+2;
if(a[i]>5000){
break;
}
}
return 0;
}
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