pvjc24/cv1/program.c

#include <stdio.h>


int main()
{
    char c;
    while ((c = getchar()) != EOF) {
        if(c<='z'&&c>='a'){
            c=c+('A'-'a');
        }else if(c<='Z'&&c>='A'){
            c=c-('A'-'a');
        }
        printf("%c",c);
    }
    printf("\n");
    return 0;
}