Compilare: user.cpp: In function ‘int main()’: user.cpp:80:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(addc[j]<vc[j].size() && vc[j][addc[j]].i==i){ ^ user.cpp:84:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(addl[j]<vl[j].size() && vl[j][addl[j]].i==i){ ^ 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("qmatrix.in","r",stdin); ^ user.cpp:25:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("qmatrix.out","w",stdout); ^ user.cpp:30:34: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d%d",&n,&x,&y,&q); ^ user.cpp:32:34: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf(" %c%d%d",&t,&k,&p); ^