UVA_12554_Happy_Birthday

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
    typedef struct reg{
         char* letter;
    }Treg;
    typedef struct reg1{
         char let[20];
    }Treg1;
    int main(int argc, char** argv) {
        Treg song[16];int n;
        song[0].letter="Happy";song[1].letter="birthday";song[2].letter="to";
        song[3].letter="you";song[4].letter="Happy";song[5].letter="birthday";
        song[6].letter="to";song[7].letter="you";song[8].letter="Happy";
        song[9].letter="birthday";song[10].letter="to";song[11].letter="Rujia";
        song[12].letter="Happy";song[13].letter="birthday";song[14].letter="to";
        song[15].letter="you";
        int cont=0;int cont1=0;int i,j;
        Treg1 singers[100];

       while(scanf("%d",&n)==1)
    {
        char buffer[20]; char buf1[20];
        for (i=0;i<20;i++) buffer[i]=0;
        for (i=0;i<20;i++) buf1[i]=0;
        for (i=0;i<n;i++){
            scanf("%s",&buffer);
            for (j=0;j<strlen(buffer);j++){
                singers[i].let[j]=buffer[j];
            }
            singers[i].let[j]='\0';

        }
        if (n<16){
            while (cont<16){
                i=0;
                while((i<n) && (cont!=16)){
                    printf("%s: %s\n",singers[i].let,song[cont].letter);
                    cont++;i++;
                }
            }
        }else{

            while(cont<n){
                i=0;
                while(i<16 && cont!=n){

                    printf("%s: %s\n",singers[cont].let,song[i].letter);
                    cont++;i++;
                }


            }
            if(cont==n && i!=16){
                cont=0;
                for(j=i;j<16;j++){
                    printf("%s: %s\n",singers[cont].let,song[j].letter);
                    cont++;i++;
                }
            }

        }
      }
        return (EXIT_SUCCESS);
    }