Compilare: user.cpp: In function ‘int main()’: user.cpp:133:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen ("pal2.in","r",stdin); ^ user.cpp:134:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen ("pal2.out","w",stdout); ^ user.cpp:135:23: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%s", (a+1)); ^ user.cpp: In function ‘void ZAlg(char*, int)’: user.cpp:88:16: warning: ‘M’ may be used uninitialized in this function [-Wmaybe-uninitialized] t=2*M-i; L=2*M-R; ^ user.cpp: In function ‘int main()’: user.cpp:168:25: warning: ‘val’ may be used uninitialized in this function [-Wmaybe-uninitialized] val=(1LL*val*X+(a[i+j+1]-'0')+1LL*(a[i-j]-'0')*powlog[2*j+1])%MOD; ^