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

#define LINE_SIZE 150
#define MAX_RLEN 50

char* read_line();
char* runLengthCod(char* line);
char* encode(char* src);
char* decode(char* line);

int main(){
    char* line = read_line();
    //char* compressedline = runLengthCod(line);
    char* compressedline = encode(line);
    char* decompressedline = decode(compressedline);
    printf("line = %s\n", line);
    printf("encoded line = %s\n", compressedline);
    printf("decoded line = %s\n", decompressedline);

    free(line); free(compressedline); 
    free(decompressedline);
    return 1;
}

char* encode(char* src) 
{ 
    int rLen; 
    char count[MAX_RLEN]; 
    int len = strlen(src); 

    char* dest = (char*)malloc(sizeof(char) * (len * 2 + 1)); 
  
    int i, j = 0, k; 
    char ch;

    for (i = 0; i < len; i++) { 
        //dest[j++] = src[i]; 

        ch = src[i];
        rLen = 1; 
        while (i + 1 < len && src[i] == src[i + 1]) { 
            rLen++; 
            i++; 
        } 
        sprintf(count, "%d", rLen); 
  
        for (k = 0; *(count + k); k++, j++) { 
            dest[j] = count[k]; 
        } 
        dest[j++]=ch;

    } 
  
    dest[j] = '\0'; 
    return dest; 
} 

char* decode(char* line){
    char* result = (char*)malloc(LINE_SIZE);
    memset(result,0,LINE_SIZE);
    int enlen = strlen(line);
    int count=0; 
    int j=0;

    for(int i=0; i<enlen; i++){

        if(isdigit(line[i])){
            count = count*10 + line[i]-'0';
        }else{
            while(count > 0){
                result[j] = line[i];
                j++;
                count--; 
            }
        }
        
    }

    return result;
}

char* read_line(){
  char* line=(char*)malloc(LINE_SIZE);

  memset(line,0,LINE_SIZE);

  char* r = fgets(line,LINE_SIZE,stdin);

    if(r==NULL||strlen(line)==1){
      free(line);
      return 0;
    }
    else if (strlen(line)==LINE_SIZE-1 && line[LINE_SIZE]!='\n')
    {
      printf("string is too long\n");
    }
    else{
      int len = strlen(line);  
      line[len-1] = '\0'; 
      return line;
    }
}