a[9],x,d,i;main(f){for(;~scanf("%d",a+i);)x=fmax(abs(a[i++]),abs(a[i-1]));for(i-=2;--i;f&=x!=a[i])d=fmax(d,a[i]);x=!printf("%d",(x+d-1)/d+(x<d&f&&x));}