#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; int num=0; cin>>n>>x>>y; num=n-y/x; if(y%x!=51) num--; if(num<=51) cout<<0<<endl; else cout<<num<<endl; return 0; }