#include <cstdio>

int main(){
    int D;
    scanf("%d", &D);

    int a[10001];
    for(int i=0;i<=D;i++){scanf("%d", a+i);}

    for(int i=D-3;i>=0;i--){
        a[i+1] += a[i+3];
        a[i+3] = 0;
    }

    int d = 0;
    for(int i=0;i<=D;i++){
        if(a[i] > 0){d = i;}
    }

    printf("%d\n", d);
    for(int i=0;i<=d;i++){
        if(i == d){printf("%d\n", a[i]);}
        else{printf("%d ", a[i]);}
    }
}