a[99],x,d,i;main(f){for(;~scanf("%d",a+i);i++)x=fmax(abs(a[i-1]),abs(a[i]));for(i-=2;--i;f&=x!=a[i])d=fmax(d,a[i]);x=!printf("%d",(x+d-1)/d+(x<d&f&&x));}