time_conversion.c

#include <stdlib.h>
#include<string.h>
#include<stdio.h>

int main() {
int hh, mm, ss;
char t12[3];
scanf("%d:%d:%d%s", &hh, &mm, &ss, t12);

if(strcmp(t12, "PM")==0 && hh != 12) hh +=12;
if (strcmp(t12, "AM")==0 && hh==12) hh = 0;

printf("%02d:%02d:%02d", hh, mm, ss);
return 0;
}