int.Parse on negative number results in exception

int.Parse on negative number results in exception

This line of code:
int.Parse("-1");
Results in a FormatException that says "Input string was not in the
correct format" when i run it on a device. On the emulator it works just
fine. I've tested this with a bunch of devices, and the only one that is
working as intended (i.e. returns an int with value -1) is the Samsung
Galaxy Nexus, running android 4.2.1. All these devices generates an
exception:
Google Nexus 7 (4.3)
Samsung S3 (4.1.2)
Samsung Galaxy Tab (4.0.4)
LG P970 (2.2.2)
HTC Sensation (2.3.4)
I also tried to download the app C#Shell from playstore on a device, and
enter the line above, the result is the same:

Do anyone know why this happens, or what can be done to resolve this issue?