#include<bits/stdc++.h>
using lint=long long;
using real=long double;
int main(){
    std::cin.tie(nullptr);std::ios_base::sync_with_stdio(false);
    std::cout.setf(std::ios_base::fixed);std::cout.precision(15);
    lint p,q,a;std::cin>>p>>q>>a;
    lint ans=-1;
    lint inf=1'000'000'000;
    if(p==q){
        ans=a==0?0:inf;
    }else if(p<q){
        lint ans=inf;
        for(lint i=1;i<100;i++){
            ans-=p*i/100>=q*100+a;
        }
    }else{
        lint l=a==0?0:(a-1)/(p-q)*100;
        ans=l;
        for(lint i=l+1;i<=std::min(inf,l+99);i++){
            ans+=p*i/100<q*i/100+a;
        }
    }
    std::cout<<ans<<'\n';
}