Compilare: main.cpp: In function 'int main()': main.cpp:25:26: warning: ignoring return value of 'int fscanf(FILE*, const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] fscanf(f,"%d",&input); ^ main.cpp:30:30: warning: ignoring return value of 'int fscanf(FILE*, const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] fscanf(f,"%d",&input); ^ main.cpp:15:15: warning: iteration 997 invokes undefined behavior [-Waggressive-loop-optimizations] vec[i]=0; ~~~~~~^~ main.cpp:13:18: note: within this loop for(int i=4;i<=1001;++i) ~^~~~~~