program1.cpp: In function 'void dfs(int)': program1.cpp:27: warning: comparison between signed and unsigned integer expressions program1.cpp: In function 'int main()': program1.cpp:46: warning: comparison between signed and unsigned integer expressions program1.cpp:46: warning: NULL used in arithmetic program1.cpp:49: warning: comparison between signed and unsigned integer expressions program1.cpp:54: warning: NULL used in arithmetic program1.cpp:56: warning: comparison between signed and unsigned integer expressions program1.cpp:68: warning: comparison between signed and unsigned integer expressions program1.cpp:68: warning: NULL used in arithmetic program1.cpp:71: warning: comparison between signed and unsigned integer expressions program1.cpp:70: warning: unused variable 'nr2'