/in/foo.cc: In function 'int DFS(int)':
/in/foo.cc:64:1: warning: control reaches end of non-void function [-Wreturn-type]
 }
 ^
/tmp/ccc0gbLu.o: In function `_GLOBAL__sub_I_sum':
foo.cc:(.text.startup+0x183): relocation truncated to fit: R_X86_64_PC32 against `.bss'
foo.cc:(.text.startup+0x1a1): relocation truncated to fit: R_X86_64_PC32 against `.bss'
collect2: error: ld returned 1 exit status