(-31908)-32627= 719 is a legitimate math problem that does not exceeded the limits of the declared variables. An int is both + and - a unsigned int is intended for positive numbers only.

To see how (-31908) - (32627) works in 16 bits we first convert the numbers to hexadecimal:
0x835C - 0x7F73
We change that to an addition problem by changing it to:
0x835C + (-0x7F73)
To negate 0x7F73 we invert the bits and add 1 (2's Complement)
0x835C + 0x808D
The result of the addition is: 0x103E9 (66537) but that gets truncated to 16 bits so the actual result is:
0x03E9 = 1001 which is greater than 1000.