Compilare: user.cpp: In function ‘int main()’: user.cpp:61:33: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("pscnv.in", "r", stdin); ^ user.cpp:62:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("pscnv.out", "w", stdout); ^ user.cpp:65:37: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d%d\n", &n, &m, &x, &y); ^ user.cpp:67:11: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(ln); ^ user.cpp: In function ‘int bs(int, int)’: user.cpp:45:9: warning: ‘last’ may be used uninitialized in this function [-Wmaybe-uninitialized] return last; ^ /tmp/ccOw3jxZ.o: In function `main': user.cpp:(.text.startup+0xa0): warning: the `gets' function is dangerous and should not be used.