g++-10 -Wall -lm -static -DEVAL -o roads -O2 roads.cpp grader.cpp -std=c++11
g++-10 -Wall -lm -static -DEVAL -o roads -O2 roads.cpp grader.cpp -std=c++14
g++-10 -Wall -lm -static -DEVAL -o roads -O2 roads.cpp grader.cpp -std=c++17