Compilare: user.cpp: In function ‘void write()’: user.cpp:57:39: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (j = 0; j < V[i].size(); ++ j) ^ user.cpp: In function ‘void read()’: user.cpp:32:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &n, &c); ^ user.cpp:38:35: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d ", &v[i][j]); ^ user.cpp: In function ‘int main()’: user.cpp:64:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("piese3.in", "r", stdin); ^ user.cpp:65:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("piese3.out", "w", stdout); ^ user.cpp:67:20: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &t); ^