Compilare: user.cpp: In function ‘bool is_good(int)’: user.cpp:35:33: warning: array subscript has type ‘char’ [-Wchar-subscripts] a = ( a * 67 + ch[ s[i] ] ) % P; ^ user.cpp:36:33: warning: array subscript has type ‘char’ [-Wchar-subscripts] b = ( b * 67 + ch[ s[i] ] ) % Q; ^ user.cpp:37:33: warning: array subscript has type ‘char’ [-Wchar-subscripts] c = ( c * 67 + ch[ s[i] ] ) % K; ^ user.cpp:44:38: warning: array subscript has type ‘char’ [-Wchar-subscripts] a = ( 1LL * ( a - ch[ s[i-f] ] * pwrP[f-1] + 70*P ) * 67 + ch[ s[i] ] ) % P; ^ user.cpp:44:77: warning: array subscript has type ‘char’ [-Wchar-subscripts] a = ( 1LL * ( a - ch[ s[i-f] ] * pwrP[f-1] + 70*P ) * 67 + ch[ s[i] ] ) % P; ^ user.cpp:45:38: warning: array subscript has type ‘char’ [-Wchar-subscripts] b = ( 1LL * ( b - ch[ s[i-f] ] * pwrQ[f-1] + 70*Q ) * 67 + ch[ s[i] ] ) % Q; ^ user.cpp:45:77: warning: array subscript has type ‘char’ [-Wchar-subscripts] b = ( 1LL * ( b - ch[ s[i-f] ] * pwrQ[f-1] + 70*Q ) * 67 + ch[ s[i] ] ) % Q; ^ user.cpp:46:38: warning: array subscript has type ‘char’ [-Wchar-subscripts] c = ( 1LL * ( c - ch[ s[i-f] ] * pwrK[f-1] + 70*K ) * 67 + ch[ s[i] ] ) % K; ^ user.cpp:46:77: warning: array subscript has type ‘char’ [-Wchar-subscripts] c = ( 1LL * ( c - ch[ s[i-f] ] * pwrK[f-1] + 70*K ) * 67 + ch[ s[i] ] ) % K; ^ user.cpp: In function ‘int main()’: user.cpp:64:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("substr.in","r",stdin); ^ user.cpp:65:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("substr.out","w",stdout); ^ user.cpp:69:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d\n",&N,&T); ^ user.cpp:70:24: warning: ignoring return value of ‘char* fgets(char*, int, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fgets(s,NMax,stdin); ^