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

int main(void) {
    FILE * input = fopen("input", "r");
//    FILE * output = fopen("outptut", "w");
    FILE * output = fopen("outptut", "a");
    char string[80];
    int a;
    char c;
    int sum = 0;
    while ((c = getc(input)) != EOF) {
        //fprintf(output, "%c", c);
        putc(c, output);
    }
    fputs("\nhi there\n", output);
    if (feof(input)) {
        printf("reached end of file\n");
    }
    fclose(input);
    input = fopen("input", "r");
    if (input == NULL) {
        printf("ooops\n");
    }
    while (fgets(string, 80, input) != NULL) {
        fputs(string, output);
    }
    fclose(input);
    input = fopen("numbers", "r");
    while(fgets(string, 80, input) != NULL) {
        sum+= atoi(string);
    }
    printf("sum is %d\n", sum);
    fclose(input);
    fclose(output);
    return 0;
}