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

int duzinaPOdniza(char s[], int od, char c){
	int k=strlen(s);
	int i;
	int brojac=0;
	for(i=od;i<k;i=i+2){
		while (s[i]==c){
			brojac++;
			i++;

		}
		break;
	}
	return brojac;
}
int MaxBrojac(char s[]){
	int i;
	int max=0;
	int c=strlen(s);
	for (i=0;i<c;i=i+2){
		if (duzinaPOdniza(s, i, s[i])> max) {
			max=duzinaPOdniza(s, i, s[i]);
		}
	}
	return max;
}

int main (){
	char s[15]="a,k,k,k,0,m,3";
	int p=strlen(s);
	int i,j;

	for (i=0;i<p;i=i+2){
		if (duzinaPOdniza(s, i,s[i])==MaxBrojac(s)){
			for(j=0;j<MaxBrojac(s);j=j+2){
				printf("%c",s[i]);
			}
		}
	}


}