#include <stdio.h>
#include <bits/stdc++.h>
#include <atcoder/all>
using namespace atcoder;
using mint = modint;
using namespace std;
#define rep(i,n) for (int i = 0; i < (n); ++i)
#define Inf 2000000000

int main(){	
	
	int A,B,T;
	cin>>A>>B>>T;
	
	int n = (T+A-1)/A;
	int cur = n*A - T;
	int ans = cur;
	
	rep(i,n){
		if(cur<A){
			cur += B-A;
		}
		else{
			cur -= A;
			ans = min(cur,ans);
		}
	}
	cout<<T+ans<<endl;
	
	return 0;
	
}