C :

#include<stdio.h>
main() {
	int n,x,a,c,d,e;
	double m;
	char b;
	scanf("%d%c%d\n",&a,&b,&c);
	scanf("%d%c%d",&d,&b,&e);
	if(b==':') {
		if(a==d) {
			n=e-c;
			m=0.5*n;
			printf("%.1f\n",m);
		}
		if(a<d) {
			n=60-c+e;
			m=0.5*n;
			printf("%.1f\n",m);
		}
	}

}

C++ :

#include<iostream> 
#include<string>
#include<iomanip>
using namespace std;
int main() 
{
	string a, b;
	cin >> a >> b;
	double deg = ((b[0] - '0') * 600 + (b[1] - '0') * 60 + (b[3] - '0') * 10 + (b[4] - '0') - (a[0] - '0') * 600 - (a[1] - '0') * 60 - (a[3] - '0') * 10 - (a[4] - '0')) * 0.5;
	cout << fixed << setprecision(1) << deg << endl;
	return 0;
}

Python :

a,b=list(map(int,input().split(":")))
c,d=list(map(int,input().split(":")))
t=c*30+(30*d/60)-(a*30+(30*b/60))
print("%.1lf"%t)