Compilare: main.cpp: In function 'int main()': main.cpp:13:33: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("grad.in","r",stdin); ^ main.cpp:14:35: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("grad.out","w",stdout); ^ main.cpp:16:21: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d\n",&n); ^ main.cpp:18:26: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%c",&s[i]); ^ main.cpp:32:36: warning: iteration 6999 invokes undefined behavior [-Waggressive-loop-optimizations] for(int i=1;i<=7000;i++) if(f[i]!=0) nr++; ~~~^ main.cpp:32:18: note: within this loop for(int i=1;i<=7000;i++) if(f[i]!=0) nr++; ~^~~~~~