/in/foo.cc: In function 'void Search2(int, int, int*, bool)':
/in/foo.cc:24:29: warning: unused variable 'j' [-Wunused-variable]
     int c=(a[0]+a[1]+u)%n,i,j;
                             ^
/usr/lib/gcc/x86_64-linux-gnu/6/../../../x86_64-linux-gnu/Scrt1.o: In function `_start':
(.text+0x20): undefined reference to `main'
/tmp/ccw0K2MN.o: In function `Search2(int, int, int*, bool)':
foo.cc:(.text+0x432): undefined reference to `Search(int, bool)'
foo.cc:(.text+0x418): undefined reference to `Search(int, bool)'
collect2: error: ld returned 1 exit status