s=input().split() n=s[0] x=s[1] y=s[2] n=int(n) x=int(x) y=int(y) if n%x !=0: e=y//x+1 if e > n: print(0) else: print(n-e) else: if e > n: print(0) else: f=n-y//x print(f)