Compilare: main.cpp: In function 'int main()': main.cpp:157:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = 0; j < a[i].size() ; ++j) f[i][a[i][j]] = j; ~~^~~~~~~~~~~~~ main.cpp:137:38: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("pensula.in", "r", stdin); ^ main.cpp:138:40: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("pensula.out", "w", stdout); ^ main.cpp:140:40: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d%lld%d%d", &n, &m, &q, &C); ^ main.cpp:144:24: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &x); ^