Compilare: user.cpp: In function ‘int main()’: user.cpp:39:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (j=0;j<v[i].size();j++,l++) ^ user.cpp:23:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("alpin.in","r",stdin); ^ user.cpp:24:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("alpin.out","w",stdout); ^ user.cpp:25:21: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d\n",&n); ^ user.cpp:28:16: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(s);char *p=s;j=1; ^ user.cpp:52:23: warning: ‘y1’ may be used uninitialized in this function [-Wmaybe-uninitialized] reconst(x1,y1); ^ user.cpp:52:23: warning: ‘x1’ may be used uninitialized in this function [-Wmaybe-uninitialized] /tmp/ccjUnkAf.o: In function `main': user.cpp:(.text.startup+0x8b): warning: the `gets' function is dangerous and should not be used.