include <stdio.h>

int main() { int n; scanf("%d",&n); int x[n]; for(int i=0;i<n;i++){ scanf("%d",&x[i]);} for(int i=0;i<n-1;i++){ if(x[i]*x[i+1]>0 ){ printf("%d %d\n",x[i], x[i+1]); }

}

}