#include<iostream> // cin\cout\endl #include<cstdio> //scanf()\printf() #include<cstring> // strcpy()\strcat()\strcmp()\strlen()\memset() #include<cmath> //sqrt()\pow()\abs()\ceil()\floor()\max()\min() using namespace std; int main(){ int n,x,y; cin>>n>>x>>y; if(y%x>0){ if(n-y/x-1<=0){ cout<<0; }else{ cout<<n-y/x-1; } }if(y%x==0){ if(n-y/x<=0){ cout<<0; }else{ cout<<n-y/x; } } return 0; }