Entering into the wrong If statement - c++

Question

the program does not enter the if statement it suppose to enter.for example when the sentence1 is oguzhan and the sentence2 is bugrahan for first characters it should enter the first if statement end substitution should be 4 but it doesn't.
#include <iostream>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <cmath>
using namespace std;
int main() {
char sentence1[50];
char sentence2[50];
int m, n, k, l;
int i, j, substitution;
cout << "Enter the first word:" << endl;
cin >> sentence1;
cout << "Enter the second word:" << endl;
cin >> sentence2;
m = strlen(sentence1);
n = strlen(sentence2);
int cost[m + 1][n + 1];
cost[0][0] = 0;
for (i = 1; i < m + 1; i++) {
cost[i][0] = cost[i - 1][0] + 2;
}
for (j = 1; j < n + 1; j++) {
cost[0][j] = cost[0][j - 1] + 2;
}
for (i = 1; i < m + 1; i++) {
for (j = 1; j < n + 1; j++) {
if ((sentence1[i - 1] == 'a' || sentence1[i - 1] == 'u' ||
sentence1[i - 1] == 'e' || sentence1[i - 1] == 'i' ||
sentence1[i - 1] == 'o') &&
(sentence2[j - 1] != 'a' || sentence2[j - 1] != 'u' ||
sentence2[j - 1] != 'e' || sentence2[j - 1] != 'i' ||
sentence2[j - 1] != 'o')) {
substitution = 4;
}
if ((sentence1[i - 1] != 'a' || sentence1[i - 1] != 'u' ||
sentence1[i - 1] != 'e' || sentence1[i - 1] != 'i' ||
sentence1[i - 1] != 'o') &&
(sentence2[j - 1] == 'a' || sentence1[i - 1] != 'u' ||
sentence1[i - 1] != 'e' || sentence1[i - 1] != 'i' ||
sentence1[i - 1] != 'o')) {
substitution = 4;
}
if (sentence1[i - 1] == sentence2[j - 1]) {
substitution = 0;
}
if ((sentence1[i - 1] == 'a' || sentence1[i - 1] == 'u' ||
sentence1[i - 1] == 'e' || sentence1[i - 1] == 'i' ||
sentence1[i - 1] == 'o') &&
(sentence2[j - 1] == 'a' || sentence2[j - 1] == 'u' ||
sentence2[j - 1] == 'e' || sentence2[j - 1] == 'i' ||
sentence2[j - 1] == 'o')) {
substitution = 3;
}
if ((sentence1[i - 1] != 'a' || sentence1[i - 1] != 'u' ||
sentence1[i - 1] != 'e' || sentence1[i - 1] != 'i' ||
sentence1[i - 1] != 'o') &&
(sentence2[j - 1] != 'a' || sentence2[j - 1] != 'u' ||
sentence2[j - 1] != 'e' || sentence2[j - 1] != 'i' ||
sentence2[j - 1] != 'o')) {
substitution = 3;
}
cost[i][j] = min(min(cost[i - 1][j] + 2, cost[i][j - 1] + 2),
cost[i - 1][j - 1] + substitution);
}
}
for (i = 0; i < m + 1; i++) {
for (j = 0; j < n + 1; j++) {
cout << cost[i][j] << " ";
}
cout << endl;
}
cout << sentence1[0];
return 0;
}

Answer 1

A condition like: sentence2[j-1]!='a'||sentence2[j-1]!='u' is always true -- no single character can be equal to both a and u, so one of these has to be true.
If you're using !=, it must almost always be joined by &&, not ||, otherwise the result will always be true, regardless of input.