Compilare: main.cpp: In function 'int main()': main.cpp:7:45: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] int main(){freopen("rangemode.in","r",stdin);freopen("rangemode.out","w",stdout);int n,m;scanf("%d %d",&n,&m);for(int i=0;i<n;i++){scanf("%d",&v[i]);} ^ main.cpp:7:81: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] int main(){freopen("rangemode.in","r",stdin);freopen("rangemode.out","w",stdout);int n,m;scanf("%d %d",&n,&m);for(int i=0;i<n;i++){scanf("%d",&v[i]);} ^ main.cpp:7:110: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] int main(){freopen("rangemode.in","r",stdin);freopen("rangemode.out","w",stdout);int n,m;scanf("%d %d",&n,&m);for(int i=0;i<n;i++){scanf("%d",&v[i]);} ^ main.cpp:7:149: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] int main(){freopen("rangemode.in","r",stdin);freopen("rangemode.out","w",stdout);int n,m;scanf("%d %d",&n,&m);for(int i=0;i<n;i++){scanf("%d",&v[i]);} ^ main.cpp:8:46: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] for(int i=0,l,r;i<m;i++){scanf("%d %d",&l,&r);l--;r--;if(bucket(l)==bucket(r)){int best=l;add_freq(l,r,best);remove_freq(l,r);sol[i]=v[best];}else{queries.push_back({l,r,i});}} ^