/tmp/ccmNCynn.o: In function `stress_test(int, int, int)':
main.cpp:(.text+0x107): undefined reference to `Num::operator+=(int)'
main.cpp:(.text+0x12d): undefined reference to `Num::operator*=(int)'
/tmp/ccmNCynn.o: In function `main':
main.cpp:(.text+0x819): undefined reference to `Num::operator+(Num const&)'
main.cpp:(.text+0x9c9): undefined reference to `Num::operator+=(Num const&)'
main.cpp:(.text+0xb0c): undefined reference to `Num::operator+=(int)'
main.cpp:(.text+0xb81): undefined reference to `Num::operator+=(int)'
main.cpp:(.text+0xd0a): undefined reference to `Num::operator+(Num const&)'
main.cpp:(.text+0xd4e): undefined reference to `Num::operator+(Num const&)'
main.cpp:(.text+0xe5c): undefined reference to `Num::operator+(Num const&)'
main.cpp:(.text+0xe9b): undefined reference to `Num::operator+(int)'
main.cpp:(.text+0xebb): undefined reference to `Num::operator+=(Num const&)'
main.cpp:(.text+0xfde): undefined reference to `Num::operator=(Num const&)'
main.cpp:(.text+0xff3): undefined reference to `Num::operator=(Num const&)'
main.cpp:(.text+0x13ad): undefined reference to `Num::operator*(Num const&)'
main.cpp:(.text+0x155d): undefined reference to `Num::operator*=(Num const&)'
main.cpp:(.text+0x16a0): undefined reference to `Num::operator*=(int)'
main.cpp:(.text+0x1715): undefined reference to `Num::operator*=(int)'
main.cpp:(.text+0x189e): undefined reference to `Num::operator*(Num const&)'
main.cpp:(.text+0x18e2): undefined reference to `Num::operator*(Num const&)'
main.cpp:(.text+0x19f0): undefined reference to `Num::operator*(Num const&)'
main.cpp:(.text+0x1a2f): undefined reference to `Num::operator*(int)'
main.cpp:(.text+0x1a4f): undefined reference to `Num::operator*=(Num const&)'
main.cpp:(.text+0x1c4b): undefined reference to `Num::operator+=(int)'
main.cpp:(.text+0x1d15): undefined reference to `Num::operator+=(int)'
main.cpp:(.text+0x1db9): undefined reference to `Num::operator*=(int)'
main.cpp:(.text+0x2115): undefined reference to `Num::operator-(Num const&)'
main.cpp:(.text+0x22c0): undefined reference to `Num::operator-=(int)'
main.cpp:(.text+0x23a2): undefined reference to `Num::operator+=(int)'
main.cpp:(.text+0x2417): undefined reference to `Num::operator-=(int)'
main.cpp:(.text+0x259f): undefined reference to `Num::operator-(Num const&)'
main.cpp:(.text+0x25e3): undefined reference to `Num::operator-(Num const&)'
main.cpp:(.text+0x26ff): undefined reference to `Num::operator-(Num const&)'
main.cpp:(.text+0x273b): undefined reference to `Num::operator-(int)'
main.cpp:(.text+0x2771): undefined reference to `Num::operator+(int)'
main.cpp:(.text+0x278b): undefined reference to `Num::operator-=(Num const&)'
collect2: error: ld returned 1 exit status