Standard I/O

    Functions: scanf, prinf, getchar

    Issues

    Scanf multiple char

    #include `<stdio.h>`
    #include `<stdlib.h>`
    
    int main(){
    	char c1, c2;
    
    	scanf("%d", &c1);
    	scanf("%d", &c2); // is skipped !
    }
    

    Resolve: use getchar()