Compilare: user.cpp: In function ‘int main()’: user.cpp:30:37: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = 0 ; j < strlen(s) ; ++j ) ^ user.cpp:14:26: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &N, &M); ^ user.cpp:28:16: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(s); ^ user.cpp:50:18: warning: ‘x’ may be used uninitialized in this function [-Wmaybe-uninitialized] ++G[x]; ^ /tmp/ccf0vxDz.o: In function `main': user.cpp:(.text.startup+0x68): warning: the `gets' function is dangerous and should not be used.