#include <stdio.h>
int main()
{
    long long m,t,s,n;
    scanf("%lld%lld%lld",&m,&t,&s);
    if(s%t!=0)
        n=m-s/t-1;
    else 
        n=m-s/t;
    if(t==0)
        n=0;
    printf("%lld",n);
    return 0;
}