Compilare: main.cpp: In function 'void dial(int, int)': main.cpp:31:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = 0; j < q[i].size(); j++) { ~~^~~~~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:47:38: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("tollroads.in", "r", stdin); ^ main.cpp:48:40: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("tollroads.out", "w", stdout); ^ main.cpp:51:32: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d %d", &n, &m, &Q); ^ main.cpp:53:35: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d %d", &aa, &b, &c); ^ main.cpp:59:28: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &aa, &b); ^