Compilare: user.cpp: In function ‘void tell(int)’: user.cpp:25:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (mod(i + 1, j) < x) ^ In file included from /usr/include/c++/5/cassert:43:0, from /usr/include/x86_64-linux-gnu/c++/5/32/bits/stdc++.h:33, from user.cpp:1: user.cpp: In function ‘int main()’: user.cpp:66:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] assert(dr <= mod(1, 1)); ^ user.cpp:35:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("summax.in", "r", stdin); ^ user.cpp:36:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("summax.out", "w", stdout); ^ user.cpp:38:40: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d%d", &t, &n, &st, &dr); ^ user.cpp:42:36: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &val(i, j)); ^