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

int main(int argc, char **argv){
    FILE *fpin1, *fpin2;
    int a, b, r1, r2;

    if(argc != 3){
        fprintf(stderr, "Usage: %s file1 file2\n", argv[0]);
        return 1;
    }
    if((fpin1 = fopen(argv[1], "r")) == NULL){
        printf("Failed to open: %s\n", argv[1]);
        exit(1);
    }
    if((fpin2 = fopen(argv[2], "r")) == NULL){
        printf("Failed to open: %s\n", argv[2]);
        fclose(fpin1);
        exit(2);
    }

    r1 = fscanf(fpin1, "%d", &a);
    r2 = fscanf(fpin2, "%d", &b);
    while(r1 == 1 && r2 == 1){
        if(a <= b){
            printf("%d\n", a);
            r1 = fscanf(fpin1, "%d", &a);
        }else{
            printf("%d\n", b);
            r2 = fscanf(fpin2, "%d", &b);
        }
    }
    while(r1 == 1){
        printf("%d\n", a);
        r1 = fscanf(fpin1, "%d", &a);
    }
    while(r2 == 1){
        printf("%d\n", b);
        r2 = fscanf(fpin2, "%d", &b);
    }
    fclose(fpin1);
    fclose(fpin2);
    return 0;
}