- #include <iostream> 
- #include <iomanip> 
- using namespace std; 
-   
- int main() { 
- 	double A,P,N; 
- 	cin >> P >> N >> A; 
- 	double res = (A-N)/(P-N)*1000; 
- 	if (res >= 0 && P != N) cout <<fixed <<setprecision(1)<< res; 
- 	else cout << -1; 
- 	return 0; 
- } 
				I2luY2x1ZGUgPGlvc3RyZWFtPgojaW5jbHVkZSA8aW9tYW5pcD4KdXNpbmcgbmFtZXNwYWNlIHN0ZDsKCmludCBtYWluKCkgewoJZG91YmxlIEEsUCxOOwoJY2luID4+IFAgPj4gTiA+PiBBOwoJZG91YmxlIHJlcyA9IChBLU4pLyhQLU4pKjEwMDA7CglpZiAocmVzID49IDAgJiYgUCAhPSBOKSBjb3V0IDw8Zml4ZWQgPDxzZXRwcmVjaXNpb24oMSk8PCByZXM7CgllbHNlIGNvdXQgPDwgLTE7CglyZXR1cm4gMDsKfQ==