prepare (1/3): 
finished

make (2/3): 
cd obj || mkdir obj
/bin/sh: 1: cd: can't cd to obj
gcc -c main.c -o obj/main.o -Wall -Wextra -pedantic -O3 -g
main.c: In function 'main':
main.c:68:5: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d %d", &edge_cnt, &vertex_cnt);
     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
main.c:73:9: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d %d %d", &edge[i].v1, &edge[i].v2, &edge[i].weight);
         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
gcc obj/main.o -o main -Wall -Wextra -pedantic -O3 -g
finished

clean (3/3): 
finished

all task finished, build successfully