Compilare: user.cpp: In function ‘big operator-(big, big)’: user.cpp:42:37: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] a.d[i] -= t + (i < b.d.size()?b.d[i]:0); ^ user.cpp: In function ‘bool operator<(big, big)’: user.cpp:22:1: warning: control reaches end of non-void function [-Wreturn-type] } ^ user.cpp: In function ‘big read()’: user.cpp:56:19: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(buffer+1); ^ user.cpp: In function ‘int main()’: user.cpp:84:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("dragonball.in","r",stdin); ^ user.cpp:85:41: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("dragonball.out","w",stdout); ^ user.cpp:86:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&n,&t); ^ /tmp/ccTQzOCb.o: In function `read()': user.cpp:(.text+0x210): warning: the `gets' function is dangerous and should not be used.