wb197@ubuntu:~/Downloads/opencv-2.4.13/modules/legacy/src$ g++ stereogc.cpp -o stereogc `pkg-config --cflags --libs opencv`
/usr/lib/gcc/x86_64-linux-gnu/5/../../../x86_64-linux-gnu/crt1.o: In function `_start':
(.text+0x20): undefined reference to `main'
collect2: error: ld returned 1 exit status