import math

x,y,r = [int(i) for i in input().split()]

x_sign = -1 if(x<0) else 1
y_sign = -1 if(y<0) else 1
if x==0 and y!=0 :
    x_max = 0
    y_max = y+r
elif x!=0 and y==0 :
    x_max = x+r
    y_max = 0
elif x==0 and y==0 :
    x_max = r/math.sqrt(2)
    y_max = x_max
else:
    x_max = x+r/(math.sqrt(1+(y*1.0/x)**2))*x_sign
    y_max = y+r/(math.sqrt(1+(x*1.0/y)**2))*y_sign

print(math.ceil(abs(x_max)+abs(y_max)))