Compilare: user.cpp: In function ‘int main()’: user.cpp:28:69: warning: operation on ‘NR’ may be undefined [-Wsequence-point] Hash1[++NR] = (Hash1[NR - 1] * 2 + s[i] - '0') % MOD; ^ user.cpp:41:70: warning: operation on ‘NR’ may be undefined [-Wsequence-point] Hash1[++NR] = (Hash1[NR - 1] * 10 + s[i] - '0') % MOD; ^ user.cpp:21:13: warning: unused variable ‘c’ [-Wunused-variable] int c; ^ user.cpp:17:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("twosets.in", "r", stdin); ^ user.cpp:18:40: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("twosets.out", "w", stdout); ^ user.cpp:19:20: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &t); ^ user.cpp:22:23: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%s", s); ^ user.cpp:34:23: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%s", s); ^